No First Use and Credible Deterrence

ABSTRACT Despite progress in reducing the number of nuclear weapons in the largest arsenals, a number of states are now looking to increase their reliance on nuclear weapons not only for deterrence, but also for coercion or war fighting. There is scant evidence that nuclear weapons are effective or well suited for these roles, and the risks of relying on nuclear weapons for more than deterrence of nuclear attack are under appreciated. We review the evolution of US nuclear strategy and assesses the prospects for establishing a policy of no first use. A no first use policy would in no way reduce deterrence of nuclear attack against the United States or its allies. Nuclear weapons are not an effective deterrent against non-nuclear attack because there are few if any scenarios in which a US threat to use nuclear weapons first in response to non-nuclear aggression against the United States or its allies would be credible. The benefits of adopting a policy of no first use include reducing the risks of accidental nuclear escalation or nuclear use from miscalculation, as well as supporting nonproliferation and disarmament efforts.


Over reliance on nuclear weapons
One need look no further than today's headlines to see how the lack of a no first use policy has increased the prospects for nuclear conflict. As with so many other things, President Donald Trump's rejection of accepted norms and codes of conduct is likely to significantly undermine America's historical position as a nonproliferation champion and already increasing the risks that nuclear weapons will be used. The situation on the Korean peninsula in particular risks accidental or miscalculated first-use of nuclear weapons by North Korea and the United States, due to a lack of restraint and overreliance on nuclear ambiguity. As a candidate Donald Trump refused to rule out the first use of nuclear weapons by the United States (Sanger, 2016) and implied his willingness to initiate nuclear weapons' use against North Korea (Fifield and Wagner, 2017). Russia's stated willingness to initiate nuclear use in Europe (Tucker, 2017), combined with their military adventurism, remains a serious concern. The poor relations between the United States and Russia and the disparity in conventional and nuclear forces and doctrine fuel these dangers. This contrasts with the consideration, reported in 2016 by the New York Times (Sanger and Broad, 2016) and the Washington Post (Rogin, 2016a) that President Obama was considering ruling out the first-use of nuclear weapons for the United States. The issue of possible first use contingencies was deeply debated in the process leading up to the 2010 Nuclear Posture Review (NPR). In the end, the President determined that the capabilities of the United States were not yet to a point where nonnuclear options were sufficient for the United States to state that the sole purpose of US nuclear weapons was to deter or respond to nuclear attacks against the United States or its allies. Instead, the NPR made clear that the United States would seek to create the conditions where a sole-purpose statement could be adopted, because it would benefit American security and the pursuit of nuclear reductions and stability. His visit to Hiroshima in May 2016 indicated his openness to the idea when he said: "among those nations like my own that hold nuclear stockpiles, we must have the courage to escape the logic of fear and pursue a world without them." 1 Former defense officials with full knowledge of America's conventional and nuclear capabilities and the threats America faces, including former Defense Secretary William Perry 2 and former Strategic Command commander and Vice Chairman of the Joint Chiefs of Staff Gen. James Cartwright (Cartwright and Blair, 2016), have spoken in favor of no first use. According to General Cartwright, "nuclear weapons today no longer serve any purpose beyond deterring the first use of such weapons by our adversaries" (Cartwright and Blair, 2016).
According to the Times and Post reports, the main reason President Obama did not adopt a policy of no first use was concern about the reaction of alliesparticularly Japan. In fact, the Washington Post reported that Prime Minister Abe personally conveyed his opposition to NFU, because he believed it could increase the likelihood of conventional conflict with North Korea or China (Rogin, 2016b). Reports indicated, however, that the Japanese concern stemmed from a belief that adopting no first use would weaken the perceived American commitment to Japan's defense. While untrue and not even directly related, this perception made rapid adoption of a no-first-use statement impossible. President Obama left office without adopting a policy of NFU or making any additional major changes to US nuclear policy.
The 2018 NPR, completed by the Trump Administration, made major changes to US declaratory nuclear policy, including steps that would increase the circumstances in which the United States would consider using nuclear weapons first (US Department of Defense, 2018). The new NPR reserves the right to use nuclear weapons first not only against nuclear weapon states in response to nonnuclear strategic attacks, but would also reserve the right to use nuclear weapons against nonnuclear weapon states. Somewhat ironically, the new NPR also notes that potential adversaries must "not miscalculate regarding the consequences of nuclear first use, either regionally or against the United States itself. They must understand that there are no possible benefits from…limited nuclear escalation. Correcting any such misperceptions is now critical to maintaining strategic stability in Europe and Asia" (US Department of Defense, 2018, VII). It is unclear why that same logic does not apply to first use by the United States. Trump, who has called for strengthening and expanding US nuclear capability 3 and seems unable or unwilling to connect how America's nuclear doctrine can influence its ability to achieve nonproliferation and disarmament outcomes, may be willing to take a far more expansive view of when he might use nuclear weapons than his predecessor.
Regardless of how President Trump will implement the nuclear strategy based on this new NPR, there are certain facts that should inform his decision, and will clearly affect the analysis of allies and experts on whatever position the United States adopts. Chief among these is the reality that, as the world's sole conventional military superpower, the United States does not need nuclear weapons to deter or respond to any nonnuclear threats to itself or its allies. The debate is not whether the United States can win a war; it is to what extent does US nuclear posture deter conflict and convince potential adversaries not to initiate conflict, and to what extent US nuclear capabilities be used to respond to nonnuclear threats. Some believe nuclear weapons are useful and even essential to deter or respond to nonnuclear aggression (Payne, 2016;Sestanovich, 2016). Others believe it is dangerous and undermines deterrence and crisis stability. 4 A key challenge for those who support no first use is working with and helping allies understand in concrete terms that such a step would enhance the credibility of US commitments to their security.
The behavior of President Trump demonstrates that words and actions can do more to affect alliance confidence and commitments than any change to US nuclear policy. Trump's disruptive statements and policies should not deflect those who seek a more stable international order that relies less, not more, on nuclear weapons threats from the task of building that more stable order. The United States, Japan, and other US allies must continue to work to enhance their security and the credibility of their alliance while reinforcing the norm against the nonuse of nuclear weapons that will enhance stability and reduce the risks of escalation.
A dialogue is needed between the United States and Japan on the role that nuclear weapons should play in our mutual defenseand in particular the question of whether and under what circumstances the United States should use or threaten to use nuclear weapons first in the defense of Japan, and under what conditions Japan would welcome the adoption of such a policy of no-first-use by United States.
US nuclear posture under President Trump is also likely to widen a growing schism in the global nonproliferation and disarmament process. The Nuclear Weapons Ban Convention, which was completed in 2017 without participation by any nuclear weapon state, may enter into force within the next few years. The Convention would outlaw possession of nuclear weapons and the use or threat of use such weapons by its signatories. There is a global campaign working to push US allies covered by nuclear extended deterrence to sign the treaty, and thereby reduce America's requirement for maintaining some of its nuclear capabilities.
The shift of US nuclear policy under President Trump to include greater reliance on nuclear weapons and more circumstances when nuclear weapons might be used will add energy and enthusiasm for supporters of the nuclear weapons ban convention. But if the United States does not need to rely on nuclear weapons in most circumstances and can reduce the role of nuclear weapons in maintaining the security of itself and its allies, doing so would be an important step toward reinforcing extended deterrent relationships because it would reduce the momentum of nuclear weapons ban convention movement. If the goal of US nuclear policy is, in part, to provide the greater assurances of our commitment to the security of Japan and other US allies, we must continue to balance our military requirements for defense and deterrence with our broader support for nonproliferation and disarmament. Over-reliance on the former and disregard for the latter can lead to domestic political decisions in countries such as Japan and in North Atlantic Treaty Organization (NATO) states to join the ban, directly weakening America's ability to protect and defend its system.

Cold war origins
Debate about first-use began soon after the end of World War II. Europe was divided between East and West, and the number of soldiers, tanks, and artillery deployed by the East was far greater than the number deployed by the West. Western European countries, which were still rebuilding after the war, did not have capacity or the will to match the perceived strength of the Soviet army. 5 The 1948 Berlin Crisis made clear that Soviet Union was aggressive and the United States would be unable to stop it through conventional means alone. After the Crisis, the United States adopted a policy of using nuclear weapons to deter or respond to a Soviet invasion of Europe.
The Soviet acquisition of nuclear weapons in 1949 did not cause the United States to abandon this policy. Rather, it caused the US to greatly accelerate the production of nuclear weapons and long-range bombers and begin the development of thermonuclear weapons in order to maintain nuclear superiority and the credibility of US threats to initiate the use of nuclear weapons.
The Eisenhower Administration placed even greater emphasis on nuclear weapons as a low-cost counter to the large armies of the Soviet Union and the Warsaw Pact. 6 In 1953, the US decided to produce and forward-deploy large numbers of tactical nuclear weaponsnuclear land mines, artillery shells, rockets, and bombsfor battlefield use in Europe. Eisenhower also adopted a policy of "massive retaliation," in which the United States promised to respond to any Soviet attack with immediate and massive nuclear retaliation, both to stop an invasion and destroy strategic targets in the Soviet Union. This was sometimes called "security on the cheap" because nuclear weapons were much less expensive than the additional troops and tanks that would be needed to match the Soviet army.
These threats were considered credible in the early 1950s because the Soviet Union did not have the capacity to strike the United States. But as Soviet nuclear capability grew and the United States homeland became more and more vulnerable to Soviet nuclear attack, the credibility of US threats to start a nuclear war came into doubt. This was often summarized in the form of a question: "Would an American president be willing to risk New York or Washington or Chicago to save London or Paris or Hamburg?" The need to convince both the Soviet Union and US allies that we would do so was a key factor driving the nuclear arms race. It led to the deployment of over 7,000 tactical nuclear weapons in Europe by the late 1960s (McNamara, 1983, 62-63). It also raised the very real possibility that, should we fail to deter a Soviet invasion, Europe would be destroyed by the very weapons that were intended to protect it.
As the Soviet Union achieved rough nuclear parity with the United States, it cast serious doubt on the credibility of US threats to use nuclear weapons first. Some European leaders worried that an American president might not carry through with the threat because it would lead to the destruction of the United States; understanding this, the Soviet Union might gamble and invade. This led the United States and NATO to undertake a series of risky policies to enhance the credibility of nuclear retaliation, in part by limiting their ability to control escalation. Hundreds of thousands of US soldiers and thousands of nuclear weapons were placed close to the border, in a "use-it-or-loseit" position vulnerable to being overrun in the early hours of an invasion.
The Soviets countered with their own large arsenal of forward-deployed tactical nuclear weapons, together with a pledge (later shown to be false) not to use nuclear weapons first. This led to the NATO decision to deploy intermediate-range groundlaunched cruise missiles and Pershing-II ballistic missiles in Europe. Because these forces could attack Moscow and other targets deep inside the Soviet Union, they were seen as "coupling" the United States more tightly to Europe, by preventing a nuclear war from being confined to Europe.

The end of the cold war
This logic collapsed with the end of the Cold War and the disintegration of the Warsaw Pact and the Soviet Union. The conventional balance of power shifted dramatically in favor of the United States and NATO. There was no longer a need to threaten to use nuclear weapons first to deter a conventional Sovietor Russianattack. Nuclear weapons were needed only to deter a nuclear attack, and even then it was not clear from where such an attack might come.
The first post-Cold-War secretary of defense, Les Aspin, ordered a review of US nuclear policy and stated that no-first-use could form the basis of a new nonproliferation policy. Unfortunately, that NPRand the two that followedrejected no first use, 7 largely due to concerns expressed by allies who had been told by US officials for decades that the US nuclear arsenal was the foundation of their security. That thinking and dogma was slow to change.
In November 1993 Russia discarded its no-first-use pledge to compensate for its perceived conventional inferiority (Schmemman 1993). It, in essence, adopted its own US-style approach to the problem of conventional inferiority. Russian reliance on threats of nuclear first-use increased with NATO expansion to Poland, Hungary, and the Czech Republic in 1999, and the Baltic states in 2004. More recently, Russia may have adopted an "escalate to de-escalate" doctrine that envisions the first use of lowyield tactical nuclear weapons in conflicts near its borders against a conventionally superior NATO force. Although Russian officials dispute this (Oliker, 2016), there is no doubt that American military officials believe it is the case and are wrestling with the implications of this policy. Russian doctrine asserts that such first use would only come if the existence of the Russian state were at risk as the result of a conventional conflict it was losing. 8 However, to American ears it is easy to imagine a Russian gamble that goes poorlyperhaps a Ukraine-style invasion of Baltic state that is forcefully repelled by NATO, including NATO attacks on Russian targets. This could prompt Putin to use nuclear weapons to forestall a humiliating defeat that might threaten his control of the Russian state. Such scenarios have driven US military planners to seek ways to deter any such first use of nuclear weapons by Russia.
The United States and its allies retain their military superiority to all potential adversaries. In the 2010 Nuclear Posture Review, the United States declared that the United States would not use or threaten to use nuclear weapons against nonnuclear weapons states that are in compliance with their nonproliferation obligations (US Department of Defense, 2010). Our conventional capabilities so outstripped that of any conceivable single or group of nonnuclear adversaries that the need to threaten the use of nuclear weapons was explicitly rejected. This statement was also central to providing a clear incentive for states to remain in compliance with their nuclear nonproliferation obligations.
For nuclear-armed states, a similar view prevailed. There was and is no need to threaten to use nuclear weapons to deter or respond to any plausible conventional attack from a nuclear-armed adversary. The NPR and the Obama team considered, but did not adopt, a policy that the sole purpose of nuclear weapons is to deter nuclear attack. It rejected "sole purpose" primarily because of concerns about how US allies might respond. But the NPR pledged to strengthen conventional capabilities and reduce the role of nuclear weapons in deterring nonnuclear attack, with the objective of making deterrence of nuclear attack on the US and its allies the sole purpose of US nuclear weapons. By 2016 much progress had been made on this effort. As a result, in his final national security speech, Vice President Biden told an audience in Washington DC that "it is hard to envision a plausible scenario in which the first use of nuclear weapons by the United States would be necessary or make sense." 9 NFU and sole-purpose, extended deterrence, and the nuclear umbrella Most analysts consider "sole purpose" to be essentially equivalent to no-first-use, because if the only purpose of nuclear weapons is to deter the use of nuclear weapons by others, then there is no reason to use or threaten to use nuclear weapons first. 10 Deterrence is no longer the core mission, but the only mission. With a policy of no-first -use or sole-purpose, the United States would use or threaten to use nuclear weapons only in retaliation to a nuclear attack on the United States or its allies, such as Japan.
If the threat to use nuclear weapons first is not necessary, it is less than fully credible. As such, making incredible threats weakens the credibility of other commitments. Abandoning incredible threats should make the remaining nuclear use scenarios, and therefore deterrence, more credible.
Deeply related to this discussion are the concepts of "extended deterrence" and "nuclear umbrella." In both cases, the idea is that United States can extend the protection of its nuclear arsenal to allies, such as Japan, South Korea, and NATO: that the United States can deter attacks on its allies by threating to retaliate with nuclear weapons. But there are two kinds of extended deterrence or nuclear umbrellas, and much of the confusion about no-first-use arises because of a failure to clearly distinguish between the two.
The first type of extended deterrence is deterrence of nuclear attack. In this case, the United States deters nuclear attack on Japan and other allies by threatening to use its own nuclear weapons in retaliation. In essence, America declares that an attack on Japan is no different than an attack on America itself. This commitment would not be undermined in any way by no-first-use because the United States would use nuclear weapons only after an adversary had already used nuclear against an ally. The US nuclear umbrella would continue to protect Japan against nuclear attack by North Korea, China, or Russia.
The second type of extended deterrence seeks to use nuclear capabilities to deter nonnuclear or conventional attacks. This was the version of extended deterrence practiced by the United States during the Cold War, in which the United States attempted to deter Soviet invasion of western Europe (or a North Korean invasion of South Korea) by threatening to respond with nuclear weapons. This form of extended deterrence is much less credible, particularly with regard to Russia or China, because the United States would be threatening to start a nuclear war with a country that had the capacity to retaliate with nuclear weapons and destroy US cities. To convince itself that its threat was seen by the other side as credible, NATO and the United States had to go to enormous lengths in the face of a nuclear-armed Warsaw Pact, including steps like the deployment of ground-based intermediate-range cruise and ballistic missiles in the 1980s that severely tested alliance cohesion and stability.
There have been serious concerns about how the potential use by an adversary of either chemical or advanced biological weapons would enter into this equation. To be sure, the future threat of biological weapons was such a concern that the 2010 NPR made clear that the negative security assurances offered could be modified in the future if nonnuclear states were to develop and use biological weapons that could approximate the impact of nuclear weapons. But it is far from clear that threatening to use nuclear weapons in response to a biological attack would be credible or have military utility (Sagan, 2000). In the case of states currently pursuing advanced biological weapons, there appears to be a similar calculation as with nuclear weaponsa conventional or security imbalance leads states to seek some way to counter America's conventional capabilities. Threatening nuclear weapons use appear uncertain to alter this calculation because it does not address the underlying driver for proliferation. While the use of an extremely virulent and deadly biological weapon agent might hypothetically lead to casualties as large or even larger than nuclear use, a nuclear response is not likely to be effective or necessary, and thus is unlikely to be effective as a deterrent.

NFU and Japan
That brings us to today. It is clear that Japan is rightly concerned about its security in the face of an aggressive North Korea with increasingly advanced nuclear and missile capabilities. Japan also has reason to be concerned about the possibility, however remote, of nuclear attack by China or Russia. However, the US strategic nuclear arsenal is a highly effective deterrent against such an attack. America has over 4000 nuclear weapons in its active stockpile, and the entire US strategic nuclear force is undergoing modernization. This aspect of the nuclear umbrella would not be diminished in any way if the United States adopted a policy of no first use. US threats to use nuclear weapons in retaliation for nuclear attacks on Japan are highly credible, because Japan is a very close ally and the US has military bases and over 100,000 troops and dependents based in Japan.
Japan's opposition to no first use is not compatible with its rhetorical support for eventual nuclear disarmament. As noted above, no-first-use is equivalent a "sole purpose" declaration. If the sole purpose of nuclear weapons is to deter to use of nuclear weapons by others, then it follows logically that a country would be willing to give up its nuclear weapons if it could be sure that all other countries had done so. If no other countries had nuclear weapons, there would be no need to have nuclear weapons to deter their use by others. But if Japan believes that the United States must be willing to threaten the first-use of nuclear weapons, it is saying that nuclear weapons are needed to deter more than nuclear attack. Even if nuclear weapons were eliminated, these other reasons would still exist. In opposing no first use, Japan is opposing the principle of nuclear disarmament.
Some might say this is not true because there are other conditions for nuclear disarmament, such as Japan facing no security threats. But saying that we can have nuclear disarmament when all countries are content to live in peace is the same as saying that nuclear disarmament is impossible.
US and Japanese opposition to no first use weakens nonproliferation. The United States and its allies are by far the strongest military alliance in the world. The United States alone spends four times more than China and 10 times more than Russia on defense; the US and its allies together account for over 70 percent of world military spending, over four times more than all adversaries and potential adversaries combined (International Institute for Strategic Studies, 2017). Because Japan is an island nation, it is easier defend than was Germany during the Cold War. If Japan believes that the United States must resort to the first-use or threat of first-use of nuclear weapons to defend it against a nonnuclear attack, what message does this send to all other countriesparticularly those that are not US allies? Countries that are weaker and harder to defend would have even more need of nuclear weapons. A policy of no first use would strengthen nonproliferation efforts; opposing no first use weakens those efforts.
The Government of Japan no doubt believes that maintaining the option of nuclear first use by the United States provides some measure of deterrence against conventional attack on Japan. The key question is how much deterrence it provides and whether these deterrence benefits are worth the price. Nuclear deterrence of conventional attack is not cost-free because such threats lack credibility. As we saw in Europe during the Cold War, actions to increase the credibility of nuclear threats have consequences, such as increasing the likelihood of nuclear war. It would be far better to strengthen conventional defenses so that there was no reason to resort to nuclear use, and to provide for a more credible deterrent.

Scenarios for first use
What is most lacking in discussions about no first use is consideration of specific scenarios. What, exactly, are the scenarios for which Japan believes that the threat of first use of nuclear weapons would be a powerful deterrent, or actual first use of nuclear weapons would be necessary to defend Japan?
The most plausible scenario today is an attack by North Korea. As we have already noted, a US nuclear response to a nuclear attack by North Korea on Japan would not be affected by a policy of no first use, and the likelihood of nuclear retaliation by the United States should deter a nuclear attack by North Korea, because it is a highly credible threat. But North Korea might launch other attacksattacks with conventionally armed missiles or special operations forces against air bases or ports necessary for the defense of South Korea, or cyberattacks that cripple Japan's economy. How does Japan imagine that the United States could use nuclear weapons in such a scenario?
Nuclear weapons are not needed to destroy the North Korean bases from which these attacks are being launched and thereby prevent further attacks on Japan. If the United States decided to use nuclear weapons first against North Korea, it would have to be supremely confident that it could destroy all of North Korea's nuclear weapons and its capacity to deliver them against South Korea or Japan. Japan almost certainly would resist any proposal by the United States to use nuclear weapons first against North Korea, knowing that it might prompt a North Korean nuclear attack against Tokyo or other Japanese cities, with horrible consequences. But if the United States and Japan do not believe that it would make sense to use nuclear weapons first, the threat to do so cannot be a credible deterrent to nonnuclear aggression by North Korea.
Perhaps most likely conflict scenario with China is in the Senkaku Islands. Both sides might send warships and fighter aircraft, fire warning shots, followed by armed conflict. What role does Japan imagine that US nuclear weapons might have in deterring or responding to such a conflict? Certainly, Japan does not imagine that the United States would actually use nuclear weapons to defend Japanese claims to uninhabited pieces of rockfor example, to attack Chinese ships or airbases involved in the conflict. This would be so obviously unnecessary and disproportionate as to consolidate world opinion against the United States and Japan. And if the United States and Japan believeas they shouldthat there is no meaningful use for nuclear weapons in such a conflict, then how can the threat to use nuclear weapons in defense of the Senkaku Islands be credible? But if the threat is not credible, it cannot be an effective deterrent.
As a final scenario, Japan might get drawn into a conflict between the United States and China, perhaps over the defense of Taiwan or in response to Chinese actions in the South China Sea. Because the United States would use air and naval bases in Japan to support its military operations against China, China might attack these bases with conventionally armed missiles. Would Japan want the United States to use nuclear weapons first in this scenario? If so, on what targets? Several Chinese missile bases deploy both, nuclear and conventionally-armed missiles; a US nuclear attack on a Chinese nuclear base could be interpreted by China as the leading edge of a firststrike designed to eliminate China's nuclear capability. China has pledged not to use nuclear weapons firsta pledge that most analysts believe China takes seriously. But they have also promised to retaliate in the event of a nuclear attack. Would Japan want the United States to respond to a conventional Chinese attack on bases in Japan with nuclear weapons, possibly triggering Chinese nuclear retaliation against Japan? If the answer is "no," then threats to do so are not credible and they have little deterrent value.

The commitment trap
We are witnessing in real time how statements and veiled threats of nuclear use -"fire and fury such as the world has never seen" (Baker and Choe 2017)can have lasting consequences. Statements by President Trump suggesting a willingness to use nuclear weapons first in a crisis with North Korea has exacerbated the risks of accidental nuclear escalation. But in even calmer times, such vague threats are ill advised. For example, US officials apparently believe that repeatedly stating or demonstrating America's willingness and ability to use nuclear weapons in response to many kinds of nonnuclear threats can be reassuring. Japan might imagine that references to nuclear weapons use, such as an American president announcing that "all options are on the table" in response to nonnuclear options might deter China or North Korea from initiating a conventional attack and make war less likely. But China and North Korea are well aware that the US has nuclear weapons; there is no need to make explicit threats. Anything that would be interpreted by themor by Japanas a direct commitment to make a nuclear threat in response to anything but the use of nuclear weapons create what has been called "a commitment trap" (Sagan, 2000). In these cases, the United States and Japan may feel compelled to follow through with a nuclear response, even if they believe it was unwise and might trigger a catastrophic an otherwise avoidable response. If we are fighting and likely to prevail in a conventional war on the Korean peninsula, using nuclear weapons could lead to a move devastating nuclear attack by the North on South Korea and stalemate any conventional conflict. Yet, failing to respond could expose past commitments to use nuclear weapons as a bluff and the call into question the credibility of the United States on all security and military matters.
That is why President Obama and many past presidents have sought to limit the conditions under which the United States might use nuclear weapons so as to not create a commitment trap that may force it into an unnecessary use of nuclear weapons. This concern, however, extends to the stated willingness to use nuclear weapons first in most scenarios. Suggesting that the United States might want or need to use nuclear weapons first in response to a conventional or some other nonnuclear threat undermines the credibility of our commitment to nuclear retaliation. It is not supported by the nature of the threat facing the alliance today, nor is it likely to in the future. Nuclear threats also do not address the driver for the pursuit of nuclear or biological weapons in the first place, since North Korea and likely China although the later to a lesser degree as time goes on, faces a conventional inferiority that drives their need to consider nonnuclear options. The threat for the United States as the conventional superior to use nuclear weapons first also calls into question US conventional capabilities, because full confidence in those would eliminate the need to threaten the use of nuclear weapons in response to anything but a nuclear attack.

Conventional preparation for conventional war
The fact that nuclear threats cannot deter most conventional attacks, and that there is no sensible use for nuclear weapons in response for such attacks, does not mean that conventional attacks cannot be deterred or prevented, or that the United States is not committed to do so.
The United States and Japan must plan on deterring and defeating conventional aggression through conventional means. They cannot and should not rely on the magic of a nuclear umbrella, because the umbrella will not be effective under these circumstances.
A pledge of no-first-use by the United States would not signal any reduction in the commitment of the United States to the security of Japan. Instead, by recognizing that nuclear weapons cannot deter most nonnuclear attacks, and by taking steps to acquire the conventional capabilities required to deter and respond to them, the security of both countries would be enhanced.

Notes on contributors
Steve Fetter is a professor in the School of Public Policy at the University of Maryland. In 2015-16, he led the national security and international affairs division in the US Office of Science and Technology Policy.
Jon Wolfsthal is director of the Nuclear Crisis Group, a Global Zero initiative to prevent the use of nuclear weapons, and a nonresident fellow at the Belfer Center at Harvard University. He was a senior director for arms control and nonproliferation at the National Security Council.