Tread with caution: Vietnam’s retaliatory and deference measures vis-à-vis assertiveness at sea

ABSTRACT As a claimant state to the South China Sea, Vietnam is known to be decisive in safeguarding its maritime territorial claims. In order to be consistent with its echoed rules-based order in the South China Sea and its defense policy of non-alignment, this study argues that Vietnam's responses vis-à-vis China's assertiveness at sea have been through the employment of divergent maritime diplomatic strategies of retaliation and deference vis-à-vis China. This study concludes; Vietnam primarily employs civilian maritime hard power assets to showcase its active presence at sea to secure recognition of its contemporary maritime capabilities; Vietnam engages in limited-coercive maritime diplomacy through its maritime constabulary forces to indicate Vietnam's decisiveness in its maritime claims; and Vietnam's co-operative maritime diplomacy is through the conduct of joint exercises and training, and goodwill visits, with its strategic partners in Southeast Asia and broader Indo-Pacific region. It concludes that Vietnam is treading with caution with the US to deter producing signals of engaging closer with the US, which can cause elevated tensions at sea. This explanatory empirical research utilizes data from AMTI and relevant secondary sources between 2010-2022 and adopts the theoretical framework of Le Miere's tripartite typology of maritime diplomacy.


Introduction
As a claimant state to the South China Sea, Vietnam is known to be decisive in safeguarding its sovereign territorial claims.Vietnam and China have engaged in limited confrontations for decades, clashing over the disputed islands of Paracel and Spratly.One of the flashpoints of the clashes is the HYSY-981 drilling rig placed by Chinese officials within the Exclusive Economic Zone (EEZ) of Vietnam (Storey, 2014).Tensions started in May 2014 and ended only two months after the mass mobilization of coast guard vessels between China and Vietnam surrounding the drilling rig.As Southeast Asian states continue to develop stronger ties with China, claimant and non-claimant states to the South China Sea have been balancing deference and defiance policies regarding maritime territorial disputes (Goh, 2016;Haacke, 2019;Jones & Jenne, 2022) (see Figure 1 on the South China Sea claims between China and Southeast Asian states).Meanwhile, Vietnam has displayed decisiveness, but one that treads with caution in the South China Sea.This article aims to decipher Vietnam's contemporary responses to maritime territorial disputes.It argues that Vietnam's decisive South China Sea policy is due to its carefully determined maritime diplomatic strategies that allow Hanoi to showcase a posture of decisiveness vis-à-vis assertiveness at sea but one that treads cautiously to avoid escalating tensions with Beijing.
Vietnam and China share a violent history regarding their respective claims in the South China Sea.Vietnam, as a socialist republic led by a Communist Party, has argued that it has held claims over the Paracel Islands (Hoan Sa) and Spratly Islands (Truong Sa) since the seventeenth century (ICG, 2021).Vietnam's contemporary claims in the South China Sea can be seen in Figures 1 and 2. Policymakers in Hanoi have long contended that their effective occupancy over the archipelagos should be enough evidence of Vietnam's historical claims over the islands (NBR, 2023).However, Beijing has not responded lightly to Vietnam's claims.In 1974, Vietnam and Chinese navies clashed on Paracel Island, leading Vietnamese forces to retreat from their position and allow China to control Paracel Island.Fourteen years later, Vietnam and China clashed again in the Spratly Islands, leading to the death of 64 Vietnamese soldiers.Since the 1951 San Fransisco Conference, Vietnam has voiced its claim to include several features of the South China Sea, including the Paracel and Spratly Islands.As a claimant state, Vietnam's history of facing China's assertiveness at sea has become the foundation of its decisive South China Sea policy as tensions continue to flare between the two states (Figure 3).In the past couple of years, the development of Vietnam's claims in the South China Sea has entered an elevated state.A unique trend is identified, with Hanoi challenging China's Nine-Dash Line claims by employing strategies similar to China's since 2013.One of the exceptional contemporary developments has been Vietnam's dredging and landfill works in the Spratly Islands, which has intensified from 2021 until now.In 2022 alone, Reuters reported that Vietnam's expansion in the South China Sea through dredging and landfill work has accumulated to approximately 170 hectares, with 220 hectares of completed new land within the decade (Reuters, 2022).As the Asia Maritime Transparency Initiative (AMTI) reported in 2022, these developments are ' … substantial and signal an intent to fortify its occupied features in the Spratlys significantly' (AMTI, 2022).Another of China's strategies followed by Vietnam is the utilization of civilian hard power assets, such as survey ships, maritime constabulary forces, and coast guards, deployed in contested waters to showcase effective occupancy at sea (Jha, 2021;Sangtam, 2021).As a result, several limited tensions have transpired between Vietnamese and Chinese officials in the Spratly and Paracel Islands.Recent developments have shown confrontations towards Chinese research ships operating within Vietnam's EEZ and conducting assertive maneuvers (Reuters, 2023;Trung, 2019).
In response to those developments, Vietnam's responses have been divergent.First, it continues to adopt a consistent response of echoing a rules-based order in the South China Sea by issuing a note verbale on 30 March 2020, expressing Vietnam's legal position in the Spratly and Paracel Islands (Diep, 2020).This article contends that Vietnam's second response towards assertiveness at sea is through the implementation of maritime diplomatic strategies, which include persuasive, coercive, and co-operative maritime diplomacy, and conducted in a manner that treads cautiously.Despite the divergences of approaches taken by Vietnam, Hanoi still ensures that the policies are consistent with Vietnam's defense doctrine of non-alignment.It embodies the 'Three Nos,' including 'no joining military alliance, no hosting of foreign bases on Vietnamese soil, and no aligning with one country against another' (Dung & Ho, 2022, p. 2).In doing so, this article contends that Vietnam has engaged in a multitude of retaliatory and deference measures: limited coerciveness through the utilization of its non-military assets at sea (retaliatory response); persuasive maritime diplomacy through the constant update of its fleets, and actively projecting power at sea (retaliatory measure); and co-operative maritime diplomacy through the management of international relations at sea by collaborating with like-minded partners to advance maritime capacity building measures (deference measures).
The empirical puzzle raised in this article thus inquires why Vietnam has decided to adopt a decisive South China Sea policy.In a time of growing contestation at the greyzone area of the South China Sea, this analysis becomes extremely useful for maritime diplomatic studies in order to comprehend strategies taken vis-à-vis tensions at sea.Several research methodologies have been adopted to address this.First, it adopts empirical explanatory research through secondary data from AMTI and relevant media resources between 2010-2022.This qualitative inquiry is then addressed under the theoretical framework of Le Miere's 2014 maritime diplomacy concept, which categorizes maritime diplomatic strategies to include persuasive, coercive, and co-operative maritime diplomacy.This article aims to reveal how Vietnam responds to tensions against China vis-à-vis the South China Sea crisis by assessing how it behaves in the maritime domain.It is not, however, attempting to explain the impact of those maritime diplomatic actions.The following section elaborates on how this research is situated in the discourse of maritime diplomacy and empirically within discussions of Vietnam's maritime diplomatic conduct.
2. Vietnam's multipronged approach vis-à-vis assertiveness at sea: a literature and theoretical review Scholarship on Vietnam's responses to China's assertiveness at sea is not scarce.Most of the literature has covered crucial elements that help academics and policymakers better understand how Vietnam copes with the long-lasting conflicts in the South China Sea.Most academics highlighted Vietnam's recent coercive turn by adopting measures similar to China in the contested waters (Gurung, 2018;Pinotti, 2015;Sangtam, 2021).Other academics such as Nguyen Thi Hanh Ha have recently translated the recent dynamics to the South China Sea dispute by arguing the need for Hanoi to adopt a relatively flexible approach, as it is difficult to predict what form of assertiveness that China would employ in the coming years (Ha, 2019).The emerging strategic studies highlighting the Sino-Vietnam contemporary relations concerning the South China Sea are indeed essential.
Nevertheless, this article references the idea posed by Rubiolo, arguing how recent strategies employed by Southeast Asian states in the South China Sea can be understood from the economic and strategic dilemma these secondary states face vis-à-vis China.Rubiolo contended that at certain times, Southeast Asian states are predicted to take retaliatory measures, especially in times of China's aggression at sea (Rubiolo, 2020).However, due to the growing interdependence of Southeast Asian states to China's lucrative economic promises and the need to maintain steady relations with the Asian giant, secondary states of Southeast Asia face a dilemma of alignment that prevents them from taking decisive actions.
An essential discourse that has developed in relation to Vietnam and China's tensions at sea is an assessment of the measures employed by Vietnamese policymakers in the face of China's aggression.Despite differences in the specific analysis of what matters most for Vietnam, the following is most argued; establishment of a rules-based order in the South China Sea, legal mechanisms, and ASEAN-based solutions.Most of the claimant states in the South China Sea are members of ASEAN.Thus, several academics have argued that a peaceful resolution to the tensions at sea could be resolved with an ASEAN-centered resolution (Dar, 2023;Shoji, 2012).Consistent with Vietnam's policymakers, some academics have contended that Vietnam's primary strategy has been to echo the importance of legal mechanisms, including reference to existing international laws, as instruments to resolve the conflict (Ha, 2019;Pietrasiak & Pieczara, 2019).This study echoes the research studies by Cooreman (2020) and Do (2021), arguing that Vietnam's strategies vis-à-vis China's Nine Dash Line claims are multifaceted/multipronged.In certain circumstances, Vietnam would echo the importance of legal instruments and issue diplomatic protests.In contrast, in others, it would strategically attempt to internationalize the issue by involving other great powers.
In alignment with that line of logic, it is difficult to confine Vietnam's strategies to simple propositions, as it is the nature of secondary states to take multiple approaches in the face of aggression.Not only is it essential to include an analysis that considers multiple elements in deciphering certain phenomena, but it is also vital to consider the emerging policies taken by Vietnam, including the development of constabulary maritime forces and the advancement of its reclamation in the Spratly and Paracel Islands.Gurung, for example, argued that Vietnam's primary strategy in managing tensions in the South China Sea is its non-alignment defense doctrine (Gurung, 2018).However, this fails to consider Vietnam's recent posture to be closer to the US and its allies due to the convergence of interests to establish a free and open Indo-Pacific.
Another discourse is the growing importance of Vietnam for partners in the Indo-Pacific.As scholars have contended, several of Vietnam's key partners in the region have favoured assisting Vietnam's development of its maritime capacities due to the growing convergence of interests that these states share.In the case of India, for example, India perceives that Vietnam's decisive posture to defend its sovereignty against China's Nine Dash Line is per India's rules-based order (ASEAN, 2020).There is also considerable literature arguing the strong likelihood that the US and Vietnam will converge interests and establish robust security relations (Fravel & Glaser, 2022;Grossman et al., 2022).
A pivotal discourse recently emerging within maritime diplomacy scholarship has been the consequences of grey-zone areas for policy decisions.This is particularly prevalent in cases related to the South China Sea, connecting this vast amount of water to the term grey-zone.Consequently, scholars such as McLaughlin and Ormsbee contended that the characterization of a certain area as a grey-zone area cultivates uncertainties about the legality of operations undertaken in the South China Sea, which has led to actions of ambiguity, belligerence, and coerciveness (McLaughlin, 2022;Ormsbee, 2022).Furthermore, these actions aimed to compel adversaries at sea are deemed problematic, considering that it does not fall under an apparent peace or war time, leading to the inability of international law to limit actions taken at sea (Azad et al., 2022).Although he did not mention grey-zone areas, Fravel's interpretation of China's South China Sea through delaying resolutions also constitutes a feature of grey-zone conflicts.As a result, the existing scholarship has made it clear that actions taken by state actors in grey-zone areas tend to indicate a negative trend, filled with actions of coerciveness.
Despite the rich scholarship that has been used to better our understanding of how Vietnam responds to China's assertiveness at sea, the existing literature still lacks a holistic assessment of the non-cooperative actions taken in the maritime domain.Thayer discussed how Vietnam is displaying retaliation but only highlights the empirical instances in which Vietnam engages in negotiation and intra-agency initiatives and neglects the vast maritime power projections taking place (Thayer, 2016).Similarly, Sangtam argued that Vietnam is no longer muted in the South China Sea conflict but purely focuses on the vocalizing of its opposition (Sangtam, 2021).Eventually, aspects in which Vietnam displays retaliation for submitting to China's claims in the South China Sea remain neglected in the literature.Such alternative perspectives fail to consider that Vietnam, empirically, has been conducting much more coercive actions than argued.
In order to unpackage this dynamic, this article employs Le Miere's conception of maritime diplomacy; persuasive, coercive, and co-operative maritime diplomacy.This theoretical framework is helpful in this instance, as due to the divergent maritime diplomatic strategies taken by Vietnam, a framework that could assess those different strategies can help reveal taken-for-granted strategies.Coercive maritime diplomacy aims to compel adversaries through limited actions of violence to achieve interests.Such maritime diplomatic behaviours are categorized in this study as retaliatory due to a state's intentions to directly contest an adversary's claims through power projections in the maritime domain.Also falling under the category of retaliatory is persuasive maritime diplomacy, an act of 'showing the flag,' displaying effective occupancy by deploying military and civilian vessels to showcase maritime power.It is categorized as such due to the intentions of state policymakers to abide by a certain international norm that may conflict with the beliefs of the adversary.
The last form is co-operative maritime diplomacy, which includes conducting humanitarian assistance/disaster relief, joint exercise and training, and goodwill visits.Empirical actions falling under this category are Vietnam's deference measures, as it takes a cooperative stance in resolving tensions with adversaries.This would be the first study to holistically include various maritime diplomatic categories in understanding Vietnam's responses vis-à-vis China's assertiveness at sea.This choice is justifiable considering that most policies taken in regard to the South China Sea happen at sea, thus urging a maritime diplomatic analysis to understand the complexities of the situation.

Limited coerciveness and showing the flag: Vietnam's coercive and persuasive maritime diplomacy
In the face of assertiveness at sea, Vietnam's responses have been highlighted by a mixture of coercive and persuasive maritime diplomacy.Coercive maritime diplomacy is a modern term for 'gunboat diplomacy.'As past scholars of gunboat diplomacy have contended, when a state undertakes gunboat diplomacy, it is attempting to threaten adversaries and coerce them to follow a pre-defined political goal aimed to be achieved by a state (Le Mière, 2011b).Past definitions introduced by Cable, Luttwak, Turner, and Allen have now been re-introduced in contemporary maritime diplomacy studies by expanding the actors involved in perpetrating coercive maritime diplomacy to include both state and non-state actors (Cable, 1994;Davidson, 2008;Luttwak, 1974;Rowlands, 2018).Therefore, contemporary coercive maritime diplomacy can be undertaken using military forces (navies) and non-military fleets (maritime constabulary forces, paramilitary, coast guards, research fleets, fishing militia, etc.).
Besides the utilization of coercive maritime diplomacy, this study further contends that Vietnam also engages in persuasive maritime diplomacy.In contrast to coercive maritime diplomacy, when a state engages in persuasive maritime diplomacy, it does not aim to deter or compel its adversaries.It simply attempts to 'show the flag,' showing a state's active presence at sea to secure recognition of its maritime capabilities.As Le Miere argues on the past effectiveness of showing the flag, ' … naval vessels are used to merely signal one's presence and capability without necessarily seeking to influence the policies of another state' (Le Miere, 2014, p. 12).There is a distinct advantage of why a developing state such as Vietnam engages in such activities.The most prominent is that as an emerging state faced with constant pressures from its great power neighbours, it is pivotal for Vietnam to secure the recognition of those powers over Vietnam's maritime capabilities.Doing so could act as a retaliatory shield from constant 'bullying at sea,' especially in troubled waters such as the South China Sea.
As introduced in this study, Vietnam faces the dilemma of safeguarding its claims in the South China Sea and showing that the policies taken represent a sense of non-alignment.Therefore, this section argues that Vietnam can balance those expectations by adopting contradictory policies of deference and retaliation.Policies of deference are an attempt by Vietnam to take peaceful maritime diplomatic strategies through engaging with foreign powers and generating peaceful signals in how they respond to assertiveness at sea.Meanwhile, its retaliatory policies are represented by the vast coercive and persuasive maritime diplomatic strategies taken to satisfy its domestic constituents and showcase Vietnam's content to protect its sovereign claims at sea.It is critical to highlight that in the past decade, Vietnam's primary strategic choice has been to use co-operative maritime diplomacy over coercive and persuasive forms of managing international relations at sea.
Despite being a minor strategy taken by Hanoi, several attempts exist to conduct coercive diplomacy vis-à-vis China's assertiveness at sea.However, it does not fall under the dominant framework of gunboat diplomacy.Coercive diplomacy is mainly undertaken through non-military stakeholders, such as Vietnam's fishing militia and Vietnamese Fisheries Resources Surveillance (VFRS).There is a strategic justification for why Vietnam's maneuvers have focused on non-military assets alternative to using its navies.Adopting maritime diplomatic maneuvers through the Vietnamese Navies risks the possibility of militarizing the conflict.The deployment of navies tends to generate an increased escalation, as attacks directed at navies indicate an attack on a state's sovereign rights.As past scholars have contended, when tensions flare among non-military assets at sea, they will not reach the same escalatory level as if navies were involved in confrontations (Greenwood & Miletello, 2022;Le Mière, 2011a;Rowlands, 2018).
Putra's study showed that one of Vietnam's primary maritime diplomatic strategies in the face of tensions with Indonesia in the North Natuna Seas is employing fishing militias and the VFRS (Putra, 2023a).The VFRS, in particular, has displayed assertive maneuvers in safeguarding its sea claims in the North Natuna Seas by deliberately deploying fishing militias guarded by the VFRS daily (Darwis & Putra, 2022;IOJI, 2022).Instances such as that can fall under the coercive maritime diplomacy category due to its intentions to push specific political goals by compelling its adversaries.The escalations between the Indonesian and Vietnamese maritime constabulary forces show that despite Vietnam's constantly adopted rhetoric of finding a peaceful resolve over the tensions, Vietnam is willing to engage in limited coercive maritime diplomacy to safeguard its sovereignty claims at sea.A similar course of action has been identified with regard to how Vietnam has handled tensions against China in the overlapping EEZ claims.
This study argues that Vietnamese officials have maintained only a limited form of coercive maritime diplomacy.The strategic disadvantage of adopting such coercive actions may cause China to increase assertiveness.A persistent consequence has been the constant use of coercive responses adopted by China vis-à-vis Vietnam's limited coercive maneuvers at sea.As Ngo Ngoc Thu reported in 2014, there have been increasing instances of Chinese vessels using high-pressure water cannons and ramming against Vietnamese vessels (The Guardian, 2014).Instances such as these limited confrontations have now evolved to emerge daily, which allows us to comprehend why Vietnam views coercive maritime diplomacy as less favourable.
How can we make sense of Vietnam's coercive maritime diplomacy?As stated previously, scholars have taken instances of Vietnam's limited aggression in the maritime domain for granted.This study argues that this retaliatory action is due to the high importance of the South China Sea issue for Vietnam.As the Vietnam 2019 White Paper explains, … unilateral actions, power-based coercion, violations of international law, militarisation, change in the status quo, and infringement upon Viet Nam's sovereignty, sovereign rights, and jurisdiction as provided in international law, have undermined the interests of nations concerned and threatened peace, stability, security, safety, and freedom of navigation and overflight in the region.(MOD, 2019, p. 19) Aspects of traditional maritime security threats, such as the issue of maritime borders in the South China Sea, have been constantly referred to in primary documents of Vietnam for the past two decades.This started with the usage of the term 'an ninh biển' (security of the sea) and, in 2019, 'maritime security,' connected to the discourse of Vietnam's national security concerns (Duong, 2021).
In contrast to Vietnam's coercive maritime diplomacy, persuasive forms of maritime diplomacy have been more favourable in the past decade.Unlike coercive maritime diplomacy, which aims to achieve specific political goals, persuasive maritime diplomacy simply aims to increase Vietnam's maritime power and capabilities, a significant feat for a developing state vis-à-vis China's great power status in the region.Vietnam's maritime diplomacy has been undertaken through three significant policies.First, the deployment of Vietnam's HQ-561 as Vietnam's hospital ship at sea.Second, through investments to legalize and deploy fishing militia and the VFRS to showcase effective occupancy.Third, Vietnam's consistent update of its military procurements.
The existing literature on persuasive diplomacy has not delved into alternative intentions as to why states engage in such actions.Besides the intention to showcase one's maritime power, arguments on 'showing the flag' simply argue that states undertake persuasive diplomacy to show that their maritime assets are present at sea.This study reveals that in times of assertiveness and facing maritime border tensions, persuasive maritime diplomacy contains the strategic function of showcasing effective occupancy in grey jurisdictions.In areas of contestation, such as the South China Sea, the constant push for claimant states to abide by UNCLOS has not generated sufficient resolve to end differences.Therefore, claimant and non-claimant states have showcased their effective occupancy over their claims by deploying military and non-military assets at sea.As China initiated decades ago, such actions aim to reflect a nation's claims over an area it argues is owned by a state.In the three cases representing Vietnam's persuasive maritime diplomacy, it is clear that Vietnam aims to showcase its effective occupancy vis-à-vis China's claims in the overlapping EEZ areas.
An advanced maritime power image is generated through Vietnam's deployment of its Khanh Hoa 01 hospital ship (the HQ-561).In alignment with the persuasive maritime diplomacy scholarship, Vietnam's HQ-561 is a soft power strategy to showcase its maritime capabilities abroad.Since its launch in April 2012, Vietnam followed the likes of the US, Russia, China, Indonesia, Brazil, and India as an exclusive group of states that engage in similar soft power diplomacy at sea (Jevsejevas, 2020).The deployment of the HQ-561 mimics China's 'Peace Ark' in 2007 and the US 'Mercy' that sails the Indo-Pacific region annually.The Khanh Hoa 01 comprises doctors and health workers and provides services for those who need medical services (both military and civilians) in the Spratly archipelago (Lan, 2021).Its operation in the Truong Sa archipelago must be noted, as it also reflects an intention of safeguarding personnel, fishermen, and residents in grey-zone areas perceived to be owned by Vietnam.
The HQ-561 represents a unique intent among Vietnam policymakers, an intention to be perceived as a state invested in advancing its maritime capabilities and transcending military purposes.The medical ship is known to be, as Senior Lieutenant Ta Trung Thanh mentions one of the advanced medical ships in Southeast Asia, and rightfully so (Lan, 2021).Only three Southeast Asian states have military hospital ships operating: Indonesia, Myanmar, and Vietnam.Indonesia for example, has successfully displayed its intent to be perceived as an advanced maritime state through converting military ships to medical ships KRI dr.Soeharso 990, KRI Semarang 594, and KRI dr.Wahidin Sudirohusodo 991.These vessels have been active in several humanitarian operations, mainly evident during the Covid-19 responses (Bramasta & Nugroho, 2022;TNI, 2016).This trend showcases Indonesia's intent to maintain its image as a maritime nation, envisioned to realize Indonesia's status as a Global Maritime Axis.In the case of Vietnam's HQ-561, its operation since 2012 indicates a similar intention to be perceived similarly.It reflects Vietnam's proactiveness at sea beyond military purposes, which is related to the image of an advanced maritime state (Hai, 2020).
Vietnam's fishing militia and VFRS are also known to be utilized to crowd the seas strategically.Vietnam officials started to perceive the importance of non-military stakeholders in safeguarding its sovereign claims at sea through the 2009 National Assembly of Vietnam.Only then did Vietnam establish the legal grounds for its maritime constabulary forces, which included surveillance of fishermen, militia, and fisheries.In 2020, it was estimated that the fishermen's militias alone consisted of approximately 8,000 ships, and it has been consistently observed that these militias were encouraged to crowd the waters in contested areas, including in the South China Sea (Giang, 2018).As the Indonesia Ocean Justice Initiative reported, Vietnam's fishing militias in disputed waters have been accompanied by the VFRS.The VFRS is a civilian government agency that operates under the auspicious of the Vietnamese Ministry of Agriculture and Rural Development.Putra's 2023 study showed that the VFRS have intentionally maneuvered around disputed waters of Indonesia and Vietnam (Putra, 2023a).By making such deployments, Vietnamese officials are aware that the presence of government agencies can effectively showcase effective occupancy but simultaneously evade possible escalations of conflict with adversaries.Therefore, Vietnam's power projection operations in the South China Sea through its fishermen militia and VFRS allow it to effectively generate an image of effective occupancy, part of Vietnam's overall persuasive maritime diplomacy strategy.
Vietnamese policymakers have not officially announced the exact number of Vietnam's fishing militia.According to a report published by the National Institute for South China Sea Studies, the approximate number is between 46,000 and 70,000 personnel, with a quarter of that number operating armed fishing boats (Jennings, 2021).However, an analysis of Vietnam's Ministry of Defense report shows that the possible number does not exceed 7,000 members (Giang, 2022).Nevertheless, despite the unprecise number, it is arguable that Vietnam's approach to advancing its fishing militia has been in the spotlight for Beijing.It is challenging to neglect the presence of the thousands of fishing militia present in contested waters since the 2009 National Assembly.It has crowded the seas during times of relative peace and increasing tensions, including during the HYSY-981 drilling rig placed by Chinese officials within the Exclusive Economic Zone (EEZ) of Vietnam (RFA, 2022).Their presence in the contested waters of the Paracel Islands represents Vietnam's intent of crowding the seas through the fishing militia.
Last, this section argues that Vietnam's constant military procurement to update its maritime power is essentially a measure to persuade adversaries of Vietnam's growing maritime capabilities.Vietnam is by no means close to China's maritime power capabilities.However, its constant procurements of maritime equipment represent its intent to update its maritime capabilities.For example, as Trung argued, Vietnam has accelerated its naval modernization since 2014 by procuring the 'Kilo-Class' Russian submarine in 2014 and 2017 (Trung, 2019).Furthermore, Vietnam's maritime prestige heightened by procuring what Jevsejavas reported, including ' … 6 submarines, 4 frigates, 8 corvettes and a number of Coast Guard vessels' (Jevsejevas, 2020).Those procurements have been completed within 15 years.
As argued within the persuasive maritime diplomacy scholarship, when states engage in this form of maritime diplomacy, states do not have a pre-conceived intention to reorient an adversary's policies.Instead, it focuses on establishing the image of the presence of the capacity of a maritime power.Vietnam's engagement to showcase its maritime power through effective occupancy via its non-military maritime assets represents an effective use of persuasive maritime diplomacy as a controlled response to China's growing assertiveness in the South China Sea.However, the specified Vietnam's responses vis-à-vis assertiveness at sea cannot make sense of Vietnam's constant establishment of cooperation among external powers in the maritime sector.In the following section, this study argues that, informed by the co-operative maritime diplomacy literature introduced by Le Miere in 2014, Vietnam's engagement through joint exercises and port visits with its external counterparts represents an instance of co-operative maritime diplomacy.

Engaging closely with partners: Vietnam's co-operative maritime diplomacy to control tensions in the South China Sea
This section argues that part of Vietnam's strategy to respond to China's assertiveness at sea is its co-operative maritime diplomacy.Co-operative maritime diplomacy, a term coined by Le Miere in 2014, includes instances of humanitarian assistance/disaster relief, training and joint exercises, goodwill visits, as well as joint maritime security operations (Le Miere, 2014).It is a maritime diplomatic category that includes a vast number of activities.In contrast to persuasive and coercive maritime diplomacy, policymakers intend to generate influence, confidence-building, and coalition-building when they engage in co-operative forms of maritime diplomacy.When a state engages in co-operative maritime diplomacy, the state and its counterpart tend to hold similar political goals.They may include using military hard power assets (navies) and civilian hard power assets (maritime constabulary forces, etc.).As Le Miere rightfully argues, ' … co-operative maritime diplomacy can, therefore, be an attempt to support soft power through the use of hard power assets … ' (Le Miere, 2014, p. 8).Therefore, co-operative maritime diplomacy can be better understood by the management of international relations at sea, through the collaboration and confidence-building measures engaged with like-minded partners in the region.
The central empirical puzzle raised in this article is why, in contrast to its Southeast Asian counterparts, Vietnam displays decisiveness in its policies in responding to China's assertiveness at sea.As argued in the previous section, the mixture of persuasive and coercive maritime diplomacy is Vietnam's way of displaying that it possesses a clear policy in responding to maritime boundary tensions in the region.Vietnam officials display coercive maritime diplomacy through the safeguarding of Vietnam's fishing militias by the VFRS, which was intentionally undertaken to gain specific political goals by compelling adversaries.Vietnam's second form of maritime diplomacy is through 'showing the flag' conduct in troubled waters, a form of persuasive maritime diplomacy of crowding the seas through the vast maritime hard power assets controlled under Hanoi.Both forms of persuasive and coercive maritime diplomacy transcend acts of randomness at sea, as they are deliberate attempts to showcase maritime capacity and display the employment of a maritime diplomatic strategy vis-à-vis China's assertiveness at sea.As part of its maritime diplomatic strategy, Vietnam's co-operative maritime diplomacy is a significant point of concern in comprehending Vietnam's maritime diplomatic maneuvers.
Vietnam has consistently engaged in co-operative maritime diplomacy with its partners in the Indo-Pacific.In recent years, these forms of maritime diplomacy have intensified to include joint exercises, joint training, and goodwill visits.Before exploring those maritime diplomatic strategies, it is also essential to argue the importance of co-operative maritime diplomacy for a middle power such as Vietnam.Vietnam has long held the stance of prioritizing establishing a rules-based order in the South China Sea, similar to its Southeast Asian counterparts.Vietnam has been among the most consistent Southeast Asian states in employing balanced measures reflecting decisiveness and non-alignment.Vietnam must be decisive in maintaining its sovereign claims in the conflicted maritime borders.In addition, ensuring its stance as a non-aligned state ensures that Vietnam is consistent with its foreign policy alignment stance and helps to assure aggressors such as China that it will not adopt radical maneuvers in disputed waters.
Vietnam needs to balance its conduct in the South China Sea, considering its dilemma of being a member of a non-confrontational regional organization in the form of ASEAN.Meanwhile, it showcases China as unwilling to relinquish its sovereign claims at sea.Co-operative maritime diplomacy allows Vietnam to achieve such aims by adopting active rhetoric for claimant states to show restraint and adhere to international law.Vietnam's echo of a rules-based order in the troubled waters can be seen by Vietnam's consistent stance to support the Declaration of the Code of Conduct of Parties in the South China Sea (DoC) and its continuous role in promoting the importance of adopting a Code of Conduct of Parties in the South China Sea (CoC) (Blazevic, 2012;Chubb, 2022).Furthermore, it has also displayed its support for the Philippines tribunal ruling.It has voiced intentions to undergo a similar resolve to end the grey zone debates involving its maritime borders (Reuters, 2023).This decisive stance is a step further to states such as Indonesia, which, despite being a non-claimant state to the South China Seas, have undergone significant military build-ups to showcase its intentions to keep the North Natuna Seas (Parameswaran 2019a;Pattiradjawane & Soebagjo, 2015).In contrast to Hanoi, Indonesia's responses to the Philippines' tribunal rulings have been rather vague (Laksmana, 2016;Putra, 2022Putra, , 2023b)).
Vietnam intensified its intentions to finalize the CoC during its ASEAN chairmanship in 2020.As reported by Jha in 2021, Vietnam's period of leadership was filled with constant referrals to finalize the two-decade debate on the CoC while pushing ASEAN states to continue to abide by the existing DoC (Jha, 2021).This recent push to further a rulesbased order in the South China Sea is consistent with Vietnam's past role that has been active in formulating the 2002 DoC (Hiep, 2013).
An investigation of what Vietnam upholds in the DoC and throughout negotiations for the CoC reveals an alignment of interests between the South China Sea rules-based order of ASEAN and Vietnam's co-operative maritime diplomacy.Le Miere's study on maritime diplomacy stipulated that co-operative maritime diplomacy holds the goals of influence-building, confidence-building, and co-operative measures.A sense of working with one another is emphasized, with Vietnam expected to take peaceful measures to respond to China's assertiveness at sea.The strategic alignment can explain why Vietnam, in recent years, has decided to finalize and advance with its maritime-related procurements from its Indo-Pacific partners in the region, mainly Japan, India, and the US.This article argues that the procurement of hard power assets from its partners is the first step that bridges the conduct of co-operative maritime diplomatic strategies taken by Vietnam.
The significance of these procurement deals between Vietnam and its Indo-Pacific partners has intensified in recent years.Since 2014, India and Japan have consistently supported the advancement of Vietnam's maritime hard power assets.India provided financial assistance for Vietnam's speed patrol boats, which in 2014, accumulated to US$100 million credits; Meanwhile, Japan transferred six coast civilian vessels for the VFRS the following year (Vu, 2023).Japan's assistance has also been in financial loans, accumulating to US$348.2 million to help build six patrol vessels (ICG, 2021).The US also aided Vietnam's maritime assets by providing Vietnam with a decommissioned US Coast Guard vessel, the Morgenthau, in 2017 (Trung, 2019).Accumulated, these acquisitions consequently led Vietnam to build stronger ties, marked with the conduct of co-operative maritime diplomacy.This article argues that Vietnam employs three forms of co-operative maritime diplomacy; Joint Exercises, joint training, humanitarian aid, and goodwill visits.
Vietnam's co-operative maritime diplomacy of joint exercises and joint training is not confined to Vietnam's aforementioned Indo-Pacific partners.It has expanded to also include Vietnam's ASEAN counterparts due to their geographic proximity.For example, the Le Quy Don, part of Vietnam's Naval Academy, was deployed to conduct joint exchanges and exercises with Southeast Asian countries such as Brunei, the Philippines, Thailand, and Cambodia in 2018 (Parameswaran, 2018).Before those voyages, the Le Quy Don also exchanged with China (Parameswaran, 2019b).The joint exercises conducted with those countries were for confidence-building measures and coalition-building.In contrast to the coercive maritime diplomacy employed by Vietnamese officials, this maritime diplomatic tactic is to avoid provocations and enhance trust.Similar to this is the HQ-561, Vietnam's military hospital ship.Since 2012, it has engaged in three naval exercises to increase confidence-building measures in responding to humanitarian crises and disaster relief situations.In the joint exercise taking place in 2014, Vietnam was among the 18 Indo-Pacific countries in attendance, including Japan, India, and Australia (Hai, 2020).
Furthermore, as mentioned previously, a continuation of Vietnam's maritime hard power asset acquisitions has been the conduct of Vietnam's co-operative maritime diplomacy with its Indo-Pacific vital partners.Since 2016, Vu has reported that India and Japan have been keen on helping Vietnam advance its maritime assets, including technological updates to its fleets (Phuong & Vu, 2017).Following these agreements, maritime cooperation has increased, including in the forms of joint exercises and joint training.Japan and Vietnam completed a number of joint exercises in the past several years, while India and Vietnam have consistently annually conducted a joint maritime exercise with Vietnam in the South China Sea since 2018.These joint efforts to advance maritime capacities include navies, coast guards, and maritime constabulary forces.
Surprisingly, Vietnam has diversified its partners in co-operative maritime diplomacy.Not only did it not confine its partnership to Southeast Asian states and its strategic partners in the Indo-Pacific, but Vietnam's co-operative maritime diplomacy also spans as far as Europe.In 2019, Vietnam and the European Union (EU) signed the Framework Participation Agreement (FPA).Vietnam's signature makes them eligible to participate in EU's maritime-based 'Common Security and Defense' missions (Jevsejevas, 2020), which in this case, allows Vietnam to be involved in EU's European Naval Force (EU NAVFOR) for operations in the Indian Ocean.
The second dominant co-operative maritime diplomatic form is goodwill visits.Le Miere contends in his study on maritime diplomacy that goodwill visit has the distinct functions of building influences and confidence-building (Le Miere, 2014).Vietnam has conducted goodwill visits with its regional partners and received goodwill visits from its counterparts.In 2019, for example, Vietnam's Le Quy Don embarked on a voyage to Indonesia and Singapore, travelling an entire month and covering approximately 2,500 nautical miles, to build its prestige and image as a notable maritime power of Southeast Asia (Parameswaran, 2019b).As mentioned earlier, contemporary Vietnam takes pride in being a non-aligned state because it has evaded attempts to allow foreign powers to be stationed in Vietnam, avoided joining forces with a foreign power in wars, and has not been involved in a military alliance.However, this article identifies an increased welcoming of foreign vessels into Vietnam's sovereign territory, including maritime hard powers of its partners (navies, coast guards, patrol boats) (Jevsejevas, 2020).To showcase Vietnam's non-alignment, it has facilitated goodwill visits from various states, including; Australia, China, India, France, Japan, South Korea, New Zealand, and the US, in the past half a decade.
The strategic reason for allowing a diverse number of states to visit Vietnam's ports is an act of treading with caution, especially with the US.The US is China's main concern regarding Indo-Pacific maritime policies.If Vietnam engages too closely with the US regarding maritime diplomatic cooperation, it would falsely generate a signal showing Vietnam's alignment with the US.Meanwhile, if Vietnam fails to cooperate with the US, it would risk missing out on valuable maritime technological advancements and being considered by the US as an ally-worthy nation in the South China Sea disputes.As a result, Vietnam is conducting what many International relations academics term 'hedging' by sending contradictory signals to a nation on its alignment choices (Hiep, 2013;Kuik, 2008).
As reported by Vu in 2023, Vietnam has been cautious of its engagements with the US in recent years (Vu, 2023).First, it joined the Rim of the Pacific Exercise (RIMPAC) and allowed a US aircraft carrier to visit Vietnam's port, the first instance in 40 years.Vietnam's participation in the RIMPAC is impactful, as it provides both the US and Vietnam to intensively discuss matters of politics and security related to maritime security.However, Hanoi has tread lightly with its US engagement, as it decided not to become involved in the 2022 RIMPAC and cancel US aircraft carrier port visits the same year.Nevertheless, at the same time, the 2023 U.S.-Vietnam Defense Policy Dialogue concluded that both states will commit to collectively tackling maritime security threats (USDOF, 2023).
The US is not a claimant state to the South China Sea.However, over the past decade, it has led a series of efforts to undermine China's Nine-Dash Line claims by conducting freedom of navigation maritime operations.Consequently, Vietnam is aware that a strong alignment would undermine its intentions of being a non-aligned state and invite the wrath of Beijing policymakers and risk a possible escalation of the tensions at sea.Vietnam understands a strong strategic convergence of interests between Washington and Hanoi, as both adopt similar stances regarding the South China Sea tensions and support a free and open Indo-Pacific (ICG, 2021).
How can we make sense of Vietnam's co-operative maritime diplomatic strategy?The following explanation from Vietnam's 2019 Defense White Paper summarizes the importance of the peaceful resolution to tensions at sea: Viet Nam resolutely and consistently protects sovereignty, sovereign rights, and jurisdiction over its waters as provided in international law.Viet Nam upholds the 'Agreement on the Basic Principles Guiding the Settlement of Sea-Related Issues' between Viet Nam and China.It continues to implement the DOC comprehensively and effectively.Viet Nam and ASEAN strive for an early conclusion of the COC with China.Viet Nam appeals to the parties concerned to keep disputes under control and take no actions that complicate the situation or expand disputes so as to preserve peace and stability in the East Sea.(MOD, 2019, p. 31) The fact the Vietnamese policymakers are willing to refrain from adopting only coercive maritime diplomatic strategies indicates that Vietnam's behaviour in the South China Sea has not abandoned its intentions of finding a peaceful way out of the tensions in contested waters.Engaging with relevant partners, and abiding by international laws of the sea are policy manifestations of Vietnam's peaceful intentions.Furthermore, in 2018, the Vietnamese Communist Party adopted the vision of making Vietnam a 'powerful maritime nation' by 2045, advancing Vietnam's blue economy potential to help accelerate its economy (VLLF, 2018).

Conclusion
Vietnam displays unique foreign policy forms as a claimant state to the South China Sea dispute.The empirical puzzle raised in this article is that, despite being a middle power and having a considerably lesser military compared to its Southeast Asian counterparts, Vietnam shows great decisiveness to its South China Sea claims.As a result, Vietnam has displayed apparent discontent with China's Nine Dash Line by openly challenging China's claims in the South China Sea.This article argues that Vietnam's decisiveness in its South China Sea claims derives from its 'tread with caution' foreign policy.
Vietnam's confidence originates from a perfectly balanced maritime diplomatic strategy to challenge China's Nine-Dash Line claims by mixing limited-coercive efforts with a dominant co-operative element emphasizing confidence-building measures and alliance-building.These maritime diplomatic strategies are taken to avoid the risk of escalating tensions with China while simultaneously allowing Vietnam to avoid the risk of openly being aligned with a great power nation.
Vietnam's maritime diplomatic strategies vis-à-vis coerciveness at sea are thus through the employment of; persuasive, coercive, and co-operative maritime diplomacy.These forms of maritime diplomacy allow Vietnam to emerge as a decisive claimant to the South China Sea dispute, but one that does not risk the possibility of escalating tensions.It provides Vietnam with consistency towards its long-held stance of advocating a rules-based order in the South China Sea and its defense doctrine of non-alignment.The three forms of maritime diplomacy undertaken by Vietnam also generate a mixture of deference and retaliatory policies to produce peaceful and decisive signals to adversaries.The maritime diplomatic literature has argued that states do not need to be consistent with the adoption of one form of maritime diplomatic form in a certain time frame.There have been circumstances in which Vietnam deployed two forms of maritime diplomatic strategies at the same time.Consequently, certain strategies can be interpreted in contrast to the assertions made in maritime diplomacy literature.Nevertheless, as the impact of such behaviours in the maritime domain is out of this study's scope, this could be an interesting point of investigation in future inquiries.
Vietnam's policies that fall under the retaliatory category are described in this study as coercive maritime diplomacy.Vietnam has showcased its attempt to threaten adversaries and coerce China to follow a pre-defined political goal, a form of compelling adversaries.This is strategically executed by non-military hard power assets under Vietnam's control, including the deployment of Vietnam's fishing militia and VFRS.Vietnam's coercive maritime diplomacy is Hanoi's way of showcasing its decisive stance in the South China Sea, as it is willing to pursue limited tensions to push back China's claims in the Spratly and Paracel Islands.
Nevertheless, this study concludes that the bulk of Vietnam's maritime diplomatic approaches have been in the form of deference maritime diplomatic strategies; persuasive and co-operative maritime diplomacy.Persuasive maritime diplomacy is conducted to 'show the flag' and present the active presence of one's maritime capacities at sea.In the past decade, Vietnam's recent engagement in maritime diplomacy has been deploying its civilian fleets to showcase effective occupancy and its constant military procurements.Co-operative maritime diplomacy is Vietnam's primary maritime diplomatic strategy in the South China Sea.As the maritime diplomacy literature shows, this form of maritime diplomacy incorporates instances of humanitarian assistance/disaster relief, training and joint exercise, goodwill visits, and joint maritime security operations.Vietnam has consistently engaged in joint exercises, joint training, and goodwill visits with its Southeast Asian and partners in the Indo-Pacific (India, Japan, US).However, as concluded in the previous section, particular caution is employed with its relation with the US, as it treads cautiously to ensure that Vietnam does not produce the signal of aligning with the US, which can cause tensions at sea.

Figure 1 .
Figure 1.China and Southeast Asian maritime claims in the South China Sea.Source: Asia Maritime Transparency Initiative (AMTI, 2023a).

Figure 2 .
Figure 2.China and Vietnam Maritime Claims in the South China Sea.Source: Asia Maritime Transparency Initiative (AMTI, 2023a).

Figure 3 .
Figure 3. Island features of the South China Sea between China and Vietnam.Source: Asia Maritime Transparency Initiative (AMTI, 2023b).