The party politics of legislative‒executive relations in security and defence policy

Abstract The move from territorial defence to ‘wars of choice’ has influenced the domestic politics of military interventions. This paper examines the extent to which both the substance and the procedure of military interventions are contested among political parties. Regarding the substance, our analysis of Chapel Hill Expert Survey data demonstrates that across European states political parties on the right are more supportive of military missions than those on the left. On the decision-making procedures, our case studies of Germany, France, Spain and the United Kingdom show that political parties on the left tend to favour strong parliamentary control whereas those on the right tend to prefer an unconstrained executive, although with differences across countries. These findings challenge the view that ‘politics stops at the water’s edge’ and contribute to a better understanding of how political parties and parliaments influence military interventions.

relations. Although scholarship discussing party positions on specific missions and/or individual countries is abundant (e.g. Kaarbo and Kenealy 2016a;Rathbun 2004;Strong 2014), there is very little systematic and comparative analysis of party-political preferences on the use of force and legislativeexecutive relations in security policies. In this paper, we examine the extent to which both the substance and the procedure of military interventions have been contested among political parties. Using quantitative and qualitative evidence, we show that the left/right axis captures the differences across political parties on both dimensions, although the national context partially qualifies the effect of party politics.
The paper proceeds in four steps. Section one reviews various explanations for why political parties disagree about military interventions rather than sharing a cross-party notion of the 'national interest' . It presents alternative propositions on the main axes of political contestation. Section two examines the plausibility of these expectations by analysing data from the Chapel Hill Expert Survey on party positioning, which covers parties from 28 European countries (Bakker et al. 2015). Section three turns to the politics of legislative-executive relations in decision-making procedures on the use of armed force by examining the party politics of legislative-executive relations in Germany, Spain, France and the United Kingdom in depth. These four countries have played important roles in military missions but represent different constitutional traditions and political-strategic cultures. The final section recaps the main findings and argues further that despite the country-specific differences, the domestic politics of military interventions cannot be fully explained without taking into account the effect of party politics along a left/right axis. Overall, this paper argues that, contrary to the commonly held assumption that 'politics stops at the water's edge' , the role of parliaments in foreign policy (the subject of this collection) is very much a point of ideological contestation among political parties.

The party politics of military missions
Political parties emerged in response to social conflict (Lipset and Rokkan 1967). In most democracies, cultural cleavages have been less influential than socio-economic ones that pit leftist against rightist parties. The former are characterised as more 'inclusive' , 'egalitarian' and as having sympathies for a strong role for the state in the economy. The opposite holds for rightist parties. Subsequent social conflicts, e.g. over the environment, have mostly been accommodated by existing cleavages (Kriesi et al. 2006). The left/right typology has also been used to characterise foreign policy positions, despite the assumption in much International Relations scholarship that domestic actors, such as political parties, have a consensus on one national interest. Left-wing parties are considered to be 'dovish' in contrast to 'hawkish' right-wing parties. Such general profiles are confirmed in studies of election manifestos. Klingemann et al. (1994), for example, find that right-wing parties are considered to be 'pro-military' whereas left-wing parties are 'anti-military' and 'pro-peace' . However, when it comes to the actual propensity to use armed force abroad, the literature is less conclusive.
Students of political parties and security policy have suggested three rationales for why political parties differ on military missions. First, foreign policies may impact on domestic policy programmes because they compete for the same resources. For this reason, Koch and Sullivan (2010: 619) argue that parties that promote the welfare state tend to oppose large armies and expensive military procurement as well as the actual use of armed force abroad.
Second, political parties may have genuine foreign policy differences that have no discernible link to domestic politics. For example, Rathbun (2004: 19) argues that some parties believe in what Robert Jervis called the 'deterrence' model of international politics whereas others subscribe to what he dubbed the 'spiral' model. According to the former, interests are best guarded by military strength and resolve; in contrast, the latter stresses empathy and 'security dilemma sensitivity' (Jervis 1976). Whereas the former translates into more 'hawkish' policies, the latter implies more 'dovish' ones.
Third, foreign policies may result from the same core values and principled beliefs that also inspire domestic policies. Rathbun (2004: 2) suggests that liberty and equality are such core values and that 'partisan debates can generally be reduced to fundamental disputes about the importance of equality and liberty, whether at home or abroad' . For example, parties emphasising equality are concerned about minorities and the underprivileged and thus favour the welfare state as well as interventions on behalf of minorities and the underprivileged abroad.
The expectations of the three rationales are therefore partly conflicting. Whereas the first two rationales suggest support for military missions to be stronger among right-wing parties than left-wing parties, the third rationale adds an important qualification: if force is used for humanitarian purpose, rather than self-defence, left-wing parties may be more supportive than rightwing parties (see Born and Hänggi 2005: 11). Anecdotal evidence includes the interventionism of Bill Clinton's Democrats as well as Tony Blair's Labour Party.
At the same time, previous research on the influence of a government's left/ right orientation on the propensity to use military force has proceeded on the assumption that the relation would be linear (see, for example, Palmer et al. 2004). However, it is not obvious that a far right political party would be more supportive of military missions than a conservative or Christian-democratic party. The former may score higher on a general preparedness to use military force but it may also be more hesitant to use such force for any goal other than territorial defence (see the country studies in Liang 2007).
Finally, 'wars of choice' may even transcend the left/right logic entirely. If military force is purportedly used to 'save strangers' (Wheeler 2000) from state-sponsored violence (as in Kosovo 1999 andin Libya 2011), to topple a dictatorship (as in Iraq in 2003) or to support a state and nation-building process (as in Afghanistan from 2001 on), the justifications resonate with 'post-materialist' values that are characteristic of a cultural cleavage, rather than a socio-economic one. In exploring this alternative hypothesis, we make use of the new politics dimension, conceptualised by Liesbet Hooghe, Gary Marks and Carole Wilson (2002), that ranges from 'green/alternative/libertarian' (GAL) to 'traditional/authoritarian/nationalist' (TAN) party positions. For example, this GAL/TAN scale is found to capture the structure of contestation on European integration better than the traditional left-right scale (Hooghe et al. 2002).
In sum, although previous research has addressed the ideological dimension of political parties' positions on interventions, theoretical expectations about the effect of party-political cleavages differ and there are few cross-national systematic comparisons. A broader investigation is necessary to assess the different rationales for parties' positions on military interventions, as modern 'wars of choice' complicate parties' positioning on these choices.

Mapping political parties' positions on military missions
The positions of political parties have been studied and coded in a series of datasets. The most widely used dataset is provided by the Manifesto Project (Volkens et al. 2015). Even though this dataset includes variables to code parties' positions on 'the military' , 'peace' and 'internationalism' , it does not include a measure of whether parties support their country's participation in military missions. In contrast, the Chapel Hill Expert Survey (CHES) included such a question in its 2010 survey. 1 In that round, more than 1000 experts were asked to place 237 political parties from 28 European states 2 on various issues and ideological dimensions. 3 In this section, we use the data collected by the CHES to map the position of political parties on military missions and to correlate them with their value on a left/right scale, on the one hand, and on a GAL/TAN scale, on the other. 4 In addition, we draw on the notion of party families to cluster parties into groups with shared core values and interests and to examine whether there are significant differences across party families. However, not all party families are of equal weight, especially not in the countries we study in more depth. For the subsequent analysis, therefore, we exclude the 'Confessional/Protestant' , ' Agrarian' and 'Regionalist/Ethnic' party families as well as all parties that are coded as not belonging to any family. Furthermore, we merged the party families 'Conservatives' and 'Christian Democrats' into one category because they occupy comparable positions on the left-right scale and on military missions, and they do not compete with each other in any of the countries studied in depth below. For most parts of our analysis, therefore, we zoom in on the differences between the main party families, namely Conservatives/Christian Democrats, Socialists, Liberals, Greens, Radical Left and Radical Right.
Figures 1 and 2 visualise the correlation between political parties' support for peace and security missions and their position on a left/right and a GAL/TAN axis respectively. Showing the positions of 237 political parties in 28 European countries, the scatterplots demonstrate that peace and security missions are highly contested. Considerable numbers of parties can be found amongst the supporters (6 and above on the y-axis) as well as amongst the opponents (4 and below on the y-axis). In both cases, the correlations are curvilinear. 5 With a view to the left/right axis, support for peace and security missions is lowest at the far left. It grows as one moves to the centre-left and reaches its peak at the centre-right. Support then declines again as one moves to the far right, although this support is higher than at the far left. Figure 2 shows that the correlation between support for military missions and a party's position on the GAL/TAN axis is also curvilinear, i.e. support is highest at the centre and declines towards both ends. In other words, both political parties that are very green/alternative/libertarian and those that are very traditional/authoritarian/nationalist tend to oppose peace and security missions.
Although both correlations are statistically significant at the 0.001 level, the left/right variable can explain a higher share in the variation among political parties' positions on peace and security missions: r 2 for left/right is 0.43 compared to 0.12 for GAL/TAN. Furthermore, even though the GAL/TAN axis is significantly correlated to parties' positions on military missions, the curvilinear relation does not confirm the theoretical expectations outlined above: the more green/alternative/libertarian parties are, the more supportive of using force to 'save strangers' they were expected to be. Instead, the CHES data suggest that high scores on GAL tend to correspond with low support for military missions. From a theoretical point, it is unclear why support for a new use of military force is highest among political parties that occupy a neutral position on a scale that is designed to capture contestation over new politics issues. Figure 3 and Table 1 examine differences in support for military missions across the main party families. As the boxplot visualises and the analysis of variance (ANOVA) demonstrates, party families differ in the degree to which they are in favour of their country participating in peace and security missions: Conservatives/Christian Democrats and Liberal parties are most supportive whereas support is lowest among political parties of the Radical Left, followed by Green and Radical Right parties. As a party family, the Social Democrats are split right in the middle with supporters and opponents of roughly equal strength.
Taken together, political parties differ widely in their support for military missions. By and large, such differences can be well captured by the established left/right dimension. However, the correlation is curvilinear: support increases as one moves along the axis from left to right but decreases again as one nears the radical right end the spectrum. Of course, the CHES data do not allow us to determine whether differences in supporting military missions stem from the expected impact on domestic policy programmes or from genuine beliefs about foreign and security policy, but they nevertheless clearly show the divide between party families.

Recalibrating legislative-executive relations in decision-making on the use of force
Given our findings that political parties systematically differ in their support for military missions, we now examine to what extent such preferences about policy translate into preferences about procedure, namely the role of parliament in deployment decisions. The notion that support for a strong parliamentary involvement in deployment decisions first and foremost comes from opponents of military missions seems intuitively plausible. It is also in line with research in conflict studies according to which parliaments have a constraining effect on the use of force (Dieterich et al. 2015;Russett 1993: 38). However, explanations of parliament's role in deployment decisions have thus far ignored a party-political dimension and instead emphasised country-specific factors such as constitutional traditions, historical experiences and the security environment (Peters and Wagner 2014). For parties on the radical right in particular,  constitutional preferences for a strong executive conflict with the instrumental support of parliament to constrain the deployment of troops. What is more, anecdotal evidence suggests that institutional self-interest may trump principled considerations. US President Obama, for example, turned from a critic of presidential authorisation of force during his 2007 election campaign to an advocate once in the White House (Fisher 2012). Parties may thus similarly stand for a stronger parliament, regardless of their substantive positions on military missions. Finally, of course, a political party's position on specific procedural reforms may be influenced by being in government or in opposition. This section examines the party politics of legislative-executive relations in decision-making on the use of force in France, Germany, Spain and the United Kingdom. These four European members of the North Atlantic Treaty Organization (NATO) have played important roles in recent military interventions and represent different constitutional traditions, systems of government and political-strategic cultures. As described in much detail elsewhere (see Kenealy 2016b, Ostermann 2016; as well as Wagner et al. 2010), the role of parliament in decision-making on the use of force has been subject to debate and change in all four countries. Our aim in this section is to examine to what extent these debates were characterised by a party-political cleavage that pitted proponents of parliamentary scrutiny and control on the left against advocates of executive discretion on the right (the appendix 1 provides an overview of the political parties, their vote share and their position on peace and security missions, as reported in the CHES).
Because party-political contestation is often triggered by changes in the security environment or major military missions, the following section is structured around such major episodes. We first look into the debates triggered by the end of the Cold War and then discuss the aftermath of the intervention in Kosovo and, even more importantly, the 2003 Iraq war. It is important to note, however, that the effects of such events were felt unevenly across these four states. The Iraq war, in particular, triggered far more controversy over decision-making procedures in Spain and the UK, where governments decided to participate despite widespread public opposition, than in France and Germany, whose governments had decided against participation. We therefore address the recalibration of legislative-executive relations in these four countries in historically defined, separate sub-sections.

Parliamentary war powers at the end of the Cold War and the challenge of 'out of area' missions
In all four countries under study, the end of the Cold War put so-called 'wars of choice' on the agenda. The US-led intervention in the Persian Gulf to end the Iraqi occupation of Kuwait in 1991 was politically supported by all four countries, not the least because it had a clear mandate from the United Nations Security Council. At the same time, Germany's policy of using armed force only for (collective) self-defence was challenged by calls to make a military contribution to 'Operation Desert Storm' .
At the time of the 1991 Gulf War, none of the parliaments under study had the authority to participate in decision-making over such a military deployment. The German constitution required parliamentary approval for the use of force in case of an armed attack ('Verteidigungsfall') but did not address UN-authorised military interventions. In a similar vein, the Spanish constitution required an authorisation by parliament 'to declare war and make peace' . 6 However, 'the prior authorisation of Parliament for the declaration of war has become an empty power since combat operations are routinely practiced without this formality' (Cortino Hueso 2003: 741). In the UK and in France, any deployment was considered the exclusive competence of the executive (referred to as 'royal prerogative' in the UK and as 'domaine réservé' in France), although the French constitution's article 35 also reserves to parliament the right to declare war. Nevertheless, French President Mitterrand decided to ask parliament for a vote in support of the French contribution, which took place on 16 January 1991, via the intermediary of a declaration of government which can be followed by a vote. However, it was commonly understood that this vote would not challenge the exclusive executive authority to decide military missions.
Amongst these four countries, the first major recalibration of legislativeexecutive relations in deployment decision-making took place in Germany. In the years following the 1991 Gulf War, the lawfulness and the political expediency of different types of missions blended into a complex debate that was almost as controversial within as among political parties. A full review of this debate is beyond the confines of this paper (for a comprehensive overview see Harnisch 2006: 235ff.). What is worth highlighting here, however, is that positions on the role of parliament indeed reflected positions on the use of force and, notwithstanding intra-party controversies, support for military missions grew towards the right of the political spectrum (with the Radical Right absent from the debate). Thus, proposals to require approval by a super-majority of twothirds of MPs were more prominent amongst Greens (Die Grünen) and Social Democrats (SPD) than amongst Christian Democrats (CDU/CSU) because the latter were more permissive as regards the out of area deployment of the Bundeswehr. The Radical Left (Die Linke) was staunchly opposed to any use of armed force except for self-defence and therefore refrained from addressing procedural issues.
The 1994 Federal Constitutional Court ruling brought a preliminary end to this debate by declaring the 'out of area' deployment of the Bundeswehr constitutional. At the same time, however, the court referred to the Bundeswehr as a 'parliamentary army' that may only be deployed after prior authorisation by the Bundestag. The combination of granting the executive the competence to deploy armed forces in new ways, on the one hand, and procedurally constraining decisions to do so by introducing a parliamentary proviso, on the other, was crucial to build broad support for Germany's new role in security and defence.
The Constitutional Court left the task of spelling out the details in a deployment law to the Bundestag. During the drafting process, the party-political controversy continued along the lines mentioned above: the Green party again suggested a two-thirds majority for peace-enforcing missions. Proposals to enhance the executive's room for manoeuvre by exempting multinational units under NATO or EU command from any parliamentary proviso were mostly made by Christian Democrats. 7 The Liberals (FDP) took a middle position by suggesting establishing a special committee that could decide on behalf of parliament in case of small or special forces deployments. In December 2004, the deployment law was adopted against the votes of Christian Democrats, Liberals and the Radical Left.
In neighbouring France, the developments in Germany were followed with great interest. After Mitterrand's indirect vote on the Gulf War, the Vedel commission on constitutional change addressed issues of parliamentary powers in foreign policy for the first time, though without resulting in constitutional changes. The next major effort at reform was the report by the socialist MP François Lamy on the parliamentary control of military missions (and other defence-related issues, such as treaties and budgets -Lamy 2000). 8 Lamy regretted parliament's non-role in the policy-making on military operations. The large increase in number of these operations at the expense of classical inter-state war rendered the right of parliament to declare war futile (Lamy 2000: 26ff., 58). Lamy deplored this state of affairs as non-transparent and lacking legitimacy; it was strongly felt that parliamentary involvement could create this legitimacy (Lamy 2000: 35). The socialist representative suggested a change in article 35 of the French constitution creating 'the obligation for the executive to attain a prior opinion of parliament for every engagement of the French forces in operations abroad' (Lamy 2000: 60, emphasis added) excluding evacuation missions, and a prior 'authorisation' (Lamy 2000: 71) for all other missions without UN mandate or for those deriving from bilateral defence treaty obligations. The effort clearly aimed at reinstating strong parliamentary control in the 'original spirit' (Lamy 2000: 61) of the declaration of war powers. The report longed for multiple avenues of parliamentary commissions and control rights (such as in-theatre information visits, regular ministerial auditions) and overall for more participation of the sovereign's representative.
Whereas the political left followed the argumentation of its rapporteur (see Lamy 2000: 78ff.), especially the right wing of parliament criticised the Lamy report's wide deviation from the basic working principles of the Fifth Republic: dispositions entailing a prior authorisation from parliament à l' allemande were considered too strong a constraint on swift action by the executive. The right further feared the revelation of top secret information to the enemy. Conversely, the Communists even wanted to extend the authorisation to all sorts of missions (Lamy 2000: 81). Hence, the way and extent of parliamentary control were fundamentally contested, with the centre-left aiming at stronger means of control than the right, and the far left wanting to change the principle of executive prerogative completely. Neither the UK nor Spain saw significant debates about a reform of deployment decision-making before the Kosovo War of 1999. In contrast, France and especially Germany experienced intense debates about the role of parliament in decisions on the use of force. In line with our expectation that preferences over procedure result from preferences over policy, left-wing parties in both countries were the main demanders of stronger parliamentary involvement whereas parties on the right voiced concerns about the executive's ability to effectively deploy troops.

The shadow of Iraq and the party politics of legislative-executive relations
After several years in which troops were deployed to rather uncontroversial peace-keeping missions, NATO's 1999 Kosovo campaign and the 2003 Iraq war were highly controversial operations. In those countries that participated in the Iraq war despite strong public opposition, the intervention was followed by discussions about parliament's role in deployment decision-making. Particularly in the British case, these debates have been well documented elsewhere (see Kaarbo and Kenealy 2016a;Mello 2016;Strong 2014). However, whereas most accounts treat the legislative and the executive as largely unitary actors, we pay special attention to the party-political dimension of these debates.
In Spain, debates about a new deployment law began already in the wake of NATO's 1999 bombing campaign against Serbian targets in Kosovo and Serbia. In contrast to the Gulf War and several peace-keeping and peace-enforcement missions since, the 'Kosovo campaign' lacked a firm mandate from the UN Security Council and thus had weak legitimisation under international law. The Radical Left (Izquierda Unida [IU]) which was categorically opposed to the NATO operation, started stressing the need for parliamentary authorisation. The Socialists (Partido Socialista Obrero Español [PSOE]), did not go as far as to defend a full-fledged authorisation procedure, but shared the criticism on the government's neglect of the parliament in defence matters (Congreso de los Diputados 1999).
However, it was the 2003 Iraq war that led all parties in opposition to request a new Law on National Defence with stronger involvement by parliament. Since the start of the US military strikes on Iraq in March 2003, the left-wing opposition had repeatedly demanded that in any case where the deployment of Spanish troops to Iraq was being considered, parliament would be consulted, given the exceptional nature of the operation -a military intervention that did not have the support of the UN and that had divided the EU. However, in July 2003 the government, led by the Partido Popular (PP), deployed 1200 soldiers to Iraq without prior debate in parliament. 9 The opposition strongly condemned this decision, accusing the government of having involved Spain in an illegal war against the wishes of parliament, and in the run-up to the March 2004 parliamentary election, the leader of the Socialists, José Luis Rodríguez Zapatero, committed to re-evaluate the role of parliament in foreign military operations if he were to become the next Prime Minister (PM).
In the convoluted context created by the Iraq fiasco and the ensuing terrorist attacks in Madrid in March 2004, the PSOE won the election and launched the approval of a new Organic Law on National Defence. 10 Besides the requirement for ex ante consultation and authorisation of troop dispatches, 11 the new law made it mandatory to hold an annual parliamentary debate about the development of international operations and laid down a series of conditions with which foreign missions must comply (e.g. previous approval by the UN or other international organisations in which Spain is a member). The left-right cleavage was again observable during the debate on this law. Despite now being in opposition, the Conservatives voted against the introduction of the parliamentary authorisation procedure for practical reasons of efficiency and security, but also on the grounds of principled motives that this law was de facto questioning the executive prerogative in foreign and defence policy granted by the Constitution. Conversely, IU and other regional left-wing parties presented amendments strengthening the parliamentary powers, such as the mention of ex ante authorisation and stricter reporting obligations, which were finally included in the law (Congreso de los Diputados 2005; see also Xuclà 2010).
The re-calibration of legislative-executive relations in the UK shows several similarities with the Spanish case. 12 Most importantly, the strengthening of parliament would be difficult to explain without reference to the 2003 Iraq war that was unpopular at the time and widely perceived as a policy failure retrospectively. As in Spain, parties on the right (including the majority of the opposition Conservative Party [CP]) supported the intervention. In contrast to Spain (and other countries), however, large parts of the Labour Party, and its PM Tony Blair in particular, were also supportive of the intervention. Like the French President in 1991, Blair (albeit reluctantly) called parliament to vote on the deployment of troops, even though there was no obligation to do so. Although contestation over the royal prerogative (with no required approval from parliament) has a long history in the UK (Joseph 2013;Poole 2010), in the twentieth century, no substantive vote on the use of military force was held after 1950 with the Korean conflict.
Significant reconsideration of the royal prerogative was prompted by the Iraq war and the decision-making process leading up to the UK's participation. Indeed, 'Blair's intransigence during 2002-2003 raised the salience of parliament's influence over military action for many MPs. The more he refused even to debate the prospect of war with Iraq, the more they demanded not just a debate but actual influence' (Strong 2014: 6; see also Strong 2015). The UK experience in Iraq cemented a growing elite consensus that parliament should be more involved to check the executive against unpopular, unwise, and potential illegal military interventions (Eyal 2008;Kaarbo and Kenealy 2016b). This elite view was promoted across party lines. Both Gordon Brown (Labour) and David Cameron (Conservative Party) indicated their support for respective reforms, yet both refrained from real change once in office (Payne 2008;Strong 2014;UK Government 2007). During both the Blair and Brown prime ministerships, several Labour MPs introduced bills calling to formalise the role of parliament in war powers, but none progressed far. 13 Two inquiries by parliamentary committees recommended greater parliamentary oversight and control in decisions to deploy UK military (House of Commons 2004;House of Lords 2006). Conservative MPs also actively supported a stronger role for parliament during the Brown government (Hansard 2007: 480). In 2007, conservative MP William Hague criticised Brown's government for lack of movement on the issue and introduced a parliamentary debate calling for the Iraq precedent to become a new norm (Strong 2014). Hague's motion passed with cross-party support and public pledges by MPs to follow the 'Iraq precedent' , but was not binding and did not legally alter the Royal Prerogative (Strong 2014).
In contrast to the other three countries discussed here, the party-political cleavage on the question of parliament's role in the use of military force appears relatively weak in the UK. Instead, there has been cross-party momentum to strengthen parliament's role in the wake of the 2003 decision to intervene in Iraq. The UK differs for two reasons. First, the British Labour party is more supportive of military missions than its counterparts in Germany, Spain and France (see CHES data in the appendix 1). Second, the frustration over the Iraq war (under a Labour PM) has led to cross-party support for an ex ante parliamentary vote (see also Kaarbo and Kenealy 2016b).

Continuing recalibrations of legislative-executive relations beyond the Iraq war
Unpopular wars are not the only triggers for recalibrating legislativeexecutive relations. As we will show in this section, parliamentary war powers have remained contested in all four countries under study. In France a major recalibration took place in the context of a comprehensive constitutional reform. Debates in Germany, Spain and the UK revolved around the precise remit and status of parliamentary war powers.
In France, a large consensus on executive leadership in foreign policy relating to the commitment to being a global power has survived from the period of the Cold War (see Cerny 1980;Vaïsse 2009: 74ff.). What drove re-calibration in France were more general considerations of 'modernising' French democracy (Ostermann 2016). The 2005 constitutional reform commission, headed by former conservative Prime Minister Edouard Balladur (commission Balladur), 14 aimed at an overall re-evaluation of the role of parliament in the French polity and politics and stronger means for the control of the executive (Une V e République plus démocratique 2007). 15 Stating that the experience of cohabitations between the president(s) and an ideologically hostile government -as had happened between the socialist Prime Minister Jospin and the conservative President Chirac between 1997 and 2002 -has shown that there is not enough clarity in the distribution of tasks in the domaine réservé, several reforms were suggested. As to the military missions, the report recommended a more timid reformulation of article 35 aiming at speedy information rights for parliament and an ex post vote on the extension of operations after a three-month period (four months in the new constitution). 16 Hence, the president's right as commander-in-chief and her accompanying prerogative for proactive engagement remains untouched. Nevertheless, the role of parliament in military operations is increased and strengthened further by the greater autonomy of parliament in its overall rights to call in ministers, ask questions, and determine its agenda (see also Blanc 2011). The analysis suggests that the left is in favour of slightly stronger constraints and means of control, but importantly, the right wing of parliament started to favour increased means of control too, although only those that do not limit executive room for manoeuvre. Hence, a party-political cleavage remains. However, on the one hand, it is mitigated by a clear acceptance of executive lead for the sake of maintaining France's role as a major global security actor (Ostermann 2016), and on the other hand this cleavage meets a centre-left Socialist Party that is not principally dismissive of military missions.
In Germany, the deployment law that entered into force in 2005 has mainly been challenged by politicians of the centre-right. Already in 2006, the Christian Democratic MP Andreas Schockenhoff argued that the deployment law was incompatible with the concept of the EU Battlegroups. Schockenhoff 's call for a revision of the deployment law was seconded by the then Minister of the Interior, Wolfgang Schäuble (CDU) and Parliamentary State Secretary in the German Federal Ministry of Defence, Christian Schmidt (CSU) (Frankfurter Allgemeine Zeitung 2007;Frankfurter Rundschau 2006). They proposed that the Bundestag approve the deployability of the German contribution to integrated forces in advance instead of having parliament decide on specific deployments. Social Democrats and Liberals immediately rebuffed this proposal. A similar proposal was made in May 2012 by Christian Democrats Andreas Schockenhoff and Roderich Kiesewetter (Schockenhoff and Kiesewetter 2012).
Christian Democrats put this question on the agenda when they negotiated a coalition treaty with the Social Democrats in 2013. Given the opposition of the Social Democrats to any changes in the current deployment legislation, the coalition treaty stipulated the establishment of a commission that would assess how parliamentary rights can be safeguarded in the face of deepening integration within NATO and the EU (Deutschlands Zukunft gestalten 2013: 171). The Greens and Radical Left refused to participate in the commission as they saw no need for any changes. The commission published its report in June 2015. It suggested a couple of minor revisions to the current deployment law, such as exempting officers in NATO or EU headquarters from its remit (Deutscher Bundestag 2015). Overall, the party-political debate in Germany over parliament's role in decisions on the use of force fully confirms the expectation that demand for a strong legislature is highest amongst left-wing parties and lowest amongst those of the centre-right.
In Spain, debates on the implementation of the 2005 Organic Law of National Defence also indicate the enduring relevance of the party-political cleavage. The new law did not specify the exact procedure of authorisation (e.g. whether in committee or plenary) or whether the sending of additional troops, the prolongation or modification of the operation would also require authorisation. The usual practice has been that first-time troop dispatches in an operation are authorised by the plenary, whereas the authorisations of the deployment of additional troops are dealt by the defence committee. On the nature of the deployments, parliament has frequently authorised the deployment of additional troops, but not the prolongation or modification of the mandate. However, this is an on-going debate and certain episodes have sparked controversy. For example, in March 2012 the conservative government did not request the authorisation of parliament for the extension of the EU naval operation Atalanta against piracy off the coast of Somalia, arguing that the objectives of the mission remained unchanged. This view was challenged by the left-wing opposition, which considered that the geographical extension of the operation to include the coastal territory implied a change in the objectives (from defensive to offensive) and new risks/consequences of the intervention (e.g. the increased risk of collateral damage) and therefore parliamentary authorisation was necessary. The Socialist group even presented a non-legislative proposal in early April 2012 urging the government to request the authorisation, but the PP, then holding an absolute majority in parliament, rejected it. In sum, as this case illustrates, left-wing parties have continued displaying a preference for a more stringent application of the parliamentary authorisation procedure than right-wing ones.
In the UK, Cameron's Conservative-Liberal Democrat coalition government (2010-2015) indicated willingness to, in the words of Foreign Secretary Hague, 'enshrine in law for the future the necessity of consulting parliament on military action' (Hansard 21 March 2011: col. 799). The Conservative leader of the House of Commons also stated: 'We will observe the existing convention that before UK troops are committed to conflict, the House of Commons should have an opportunity to debate and vote on the matter, except when there is an emergency' (Hansard 31 January 2013: col. 1059). Cameron's decision to hold a vote on Libya, however, sent mixed messages since the vote occurred after UK participation in the airstrikes began. Frustrated MPs secured an assurance from Hague that, in future, parliament would be recalled to vote prior to any deployment (Strong 2014). During 2013, as Cameron signalled his desire to intervene in some capacity in Syria, the issue of parliament's role resurfaced. There was some confusion, however, from within the cabinet. Although Hague promised that any form of intervention, even if amounting to no more than arming the Syrian rebels, would be subject to a parliamentary vote (The Guardian 2013), Cameron maintained that the government reserved the 'ability to act very swiftly' and without parliamentary approval (BBC 2013). Testifying to the House of Lords, Deputy PM Nick Clegg indicated that 'there was a debate within Government about how to formalise and enshrine the convention. He said that he was in favour of making the convention as strong and fixed as possible, but others were more cautious' (House of Lords 2013). It was unclear if the debate was between or within parties, but given previous statements by party leaders, it was most likely both.
Taken together, all four countries under study have experienced continued debates about parliament's role in deployment decision-making. These debates have had different triggers, ranging from participation in an unpopular war to multinational military integration and constitutional reform. With the exception of the UK, however, debates in the countries under study all show a pronounced left/right cleavage, with the left demanding or defending a strong parliament and the right favouring executive room for manoeuvre.

Conclusion
This paper contributes to the study of legislative-executive relations in security and defence policy by adding a party-political dimension to the analysis. Contrary to the widely held assumption in international relations literature that national interests override party-political visions over foreign policy, our analysis shows that support for military missions systematically differs across political parties in Europe (for a similar finding on Japan see Sakaki and Lukner 2016). However, in contrast to existing studies that assume a linear correlation between parties' position on a left/right scale and support for military missions, our analysis maintains that the relationship is curvilinear: centre-right parties are more supportive than centre-left parties, which in turn are more supportive than parties on the far left and the far right.
By examining debates and reforms of legislative-executive relations in France, Germany, Spain and the UK in depth, we further demonstrate that political debates over parliament's role in deployment decision-making are heavily influenced by preferences over substantive policy: as a general rule, parliamentary war powers have been demanded and defended by political parties that are rather lukewarm or sceptical about the use of armed forces. In contrast, parties that support military missions tend to advocate executive freedom and a more limited parliamentary involvement. Although the left/right cleavage in general extends to debates about legislative-executive relations, our analysis also shows that the terms of these debates differ considerably across countries. On one end of the spectrum, the German debate departs from a broad consensus that military missions require prior parliamentary approval and revolves around possible exemptions from this generally accepted rule. On the other end of the spectrum, the French debate discusses alternative forms of parliamentary involvement short of an ex ante veto power. The debates in Spain and the UK are located between the French consensus about executive dominance and the German one about the armed forces as a 'parliamentary army' .
The different terms of debate are certainly no surprise to scholars of political culture and national identity. Elizabeth Kier (1997: 24), for one, argues that 'we cannot just assume that all left-wing parties prefer the same policies … they must be understood within their cultural context' . For example, 'unlike some Left or Socialist Parties in Europe, the French Left, born in and inspired by revolution, has never been anti-militaristic or pacifistic' (Kier 1997: 59; as well as Geis et al. 2013). Students of political culture, however, will have difficulty accounting for the significant reforms of legislative-executive relations in some of the countries we examined.
The deployment of armed forces for purposes other than self-defence has been contested amongst political parties in European countries. Party politics is not only an essential element of the domestic politics of military missions but it also impacts the recalibration of legislative-executive relations.

Notes
1. Under the heading 'position towards international security and peace keeping missions' , experts are asked to determine a political party's position on a scale from 0 ('strongly favours COUNTRY troop deployment') to 10 ('strongly opposes COUNTRY troop deployment'). The questionnaire refrains from any further specification in order to capture the full spectrum of military missions from classic United Nations peacekeeping to interventions without a Security Council mandate such as in Kosovo 1999 andIraq 2003. For this paper we have reversed the scale and recoded the 'international_security' variable into a support_mission variable that ranges from 0 (strongly opposes) to 10 (strongly favours). 2. The survey includes all (then) EU member states plus Croatia, Norway and Switzerland but excludes Luxemburg, Malta and Cyprus. Included are political parties that obtain at least 3 per cent of the vote in the national election immediately prior to the survey year or that elect at least one representative to the national or European parliament. 3. For a detailed discussion of the survey's validity and reliability see Hooghe et al. (2010). 4. In order to map political parties' position on a left/right axis, experts are asked 'Please tick the box that best describes each party's overall ideology on a scale ranging from 0 (extreme left) to 10 (extreme right). On GAL/TAN, experts are asked: 'Parties can be classified in terms of their views on democratic freedoms and rights. Libertarian or postmaterialist parties favour expanded personal freedoms, for example, access to abortion, active euthanasia, same-sex marriage, or greater democratic participation. Traditional or authoritarian parties often reject these ideas; they value order, tradition, and stability, and believe that the government should be a firm moral authority on social and cultural issues' (Bakker et al. 2015: 144). 0 indicates extreme GAL and 10 extreme TAN. 5. In both cases, the best curve estimation is a quadratic one, which is statistically highly significant (p < 0.001). 6. Constitution of Spain, article 63(3). 7. Then Minister of Defence Rudolf Scharping showed some sympathy for this proposal but ultimately endorsed the joint Socialist/Green proposal that took pride in not granting exceptions. 8. The Lamy report contains a valuable discussion held in the defence committee, which can count as a barometer for party positions.