It is no longer a question of if but when Japan and South Korea will acquire independent nuclear deterrents within the U.S. alliance system. That system would otherwise loosen in East Asia as the United States’ extended deterrence—the so-called nuclear umbrella—erodes due to China’s and North Korea’s acquisition of second strike capabilities targeting the U.S. mainland. To acquire nuclear weapons will be a politically difficult and highly fraught decision—much more so for Japan than for South Korea, where opinion polls already show considerable support. But regardless of public opinion, changes in the global and regional strategic environment are inexorably pushing both countries in this direction. Resisting the logic of these changes could lead to very grave geopolitical consequences.
In democracies, security policy must rest on a foundation of public support. Such a foundation does not yet exist in Japan on the nuclear question. It is therefore imperative that Japan engage in an open, realistic, and timely public debate to build a national consensus on this vital issue. Japanese Prime Minister Sanae Takaichi took a first step in this direction earlier this month, when she announced that her government is considering a review of Japan’s long-standing policy on hosting nuclear weapons.
The peculiarity of nuclear strategy—for Japan as for anyone else—is that it is almost entirely based not on experience but on abstract logic. Nuclear weapons have only been used twice in war—and only under circumstances that are unlikely to occur again. Despite a close call during the 1963 Cuban missile crisis and the more recent nuclear saber-rattling by Russia over its war in Ukraine, no one has any practical experience of the use of nuclear weapons in the 80 years since the attacks on Hiroshima and Nagasaki. Thankfully.
Soldiers from the Japanese Air Self-Defense Force set up missile systems during a drill at at Yokota Air Base in Tokyo on Aug. 29, 2017. Toru Yamanaka/AFP via Getty Images
Since 1945, the stability of East Asia, and particularly Northeast Asia, has rested on an equilibrium held up by Washington’s military presence and commitment to defend its allies. Since 1949, when the Soviet Union broke the U.S. nuclear monopoly, U.S. extended deterrence—the so-called nuclear umbrella over Washington’s allies—has been a vital component of this equilibrium. China’s successful nuclear test in 1964 underlined the crucial role of extended deterrence.
Japan is seriously concerned about North Korea’s nuclear and missile programs and China’s build-up and modernization of its nuclear forces. But the public discussion in Japan largely circles around these issues rather than addressing them. The essential premise of most public discussion still seems to be Tokyo’s three non-nuclear principles from 1967: non-possession, non-production, and non-introduction.
Japan’s nuclear allergy is understandable; it is the only country to have suffered a nuclear attack. But there have been profound changes in regional and global geopolitics since the three principles were formulated, which makes revisiting them appropriate. The Indo-Pacific, it is now clear, will play a central role in what Yale University scholar Paul Bracken calls a “second nuclear age,” in which regional powers will feature more prominently.
Japan’s application of its three non-nuclear principles has always been subject to practical considerations. The U.S. deployed nuclear weapons at its air base in Okinawa and did not withdraw them until the island reverted to full Japanese sovereignty in 1972. Washington did not publicly acknowledge the presence of nuclear weapons on Okinawa until 1971, but documents declassified in 2010 revealed that successive Japanese governments had been aware of and secretly complicit in these deployments for decades. Even today, the official U.S. policy is to neither confirm nor deny the presence of nuclear weapons on naval vessels and aircraft allowed into Japanese ports and airspace. Japanese governments have wisely asked no inconvenient questions, thereby facilitating U.S. nuclear deterrence in East Asia while maintaining the three non-nuclear principles.
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A silhouetted figure with a military hat is seen in front of a high red wall at night. A silhouetted figure with a military hat is seen in front of a high red wall at night. Has China’s Power Peaked in Asia?
Beijing finds itself in a precarious geopolitical position.
Japan has continually stressed its reliance on the “full range” of U.S. military capabilities—a euphemism for nuclear weapons—to maintain deterrence. While the centrality of the U.S. alliance to Japanese foreign and defense policies is unquestionable, Tokyo’s reliance on U.S. extended deterrence has also never been unhedged. Since 1957, when then-Prime Minister Nobusuke Kishi instructed the Cabinet Legislation Bureau to formally pronounce that Japan’s Constitution did not prohibit Japan possessing nuclear weapons for self-defense, Japan has maintained the foundations of a nuclear weapons program, including a stockpile of plutonium and the maintenance of reprocessing and enrichment capabilities. Washington has tacitly acquiesced in this because the U.S.-Japan Nuclear Cooperation Agreement of 1988 allows the reprocessing of U.S.-supplied nuclear material, the only treaty with any country to do so. It was therefore unsurprising when, in 2013, Japan declined to sign an international statement declaring, among other things, that nuclear weapons were inhumane and should never be used under any circumstances. The refusal made explicit what had been implicit for decades: Successive Japanese governments did indeed believe that some circumstances might warrant Japan acquiring nuclear weapons.
Japan can almost certainly produce a nuclear device in short order—perhaps within a year or less. Weaponization and the development of reliable missile delivery systems, however, would likely take considerably longer. This time-lag—experts are divided over its duration—makes postponing a public nuclear weapons debate a luxury that Japan can no longer afford.
The issue is pressing due to three factors that are rapidly changing the global and regional strategic environment. First, Washington is in the process of unilaterally redefining the terms of its engagement with the world. Second, China’s nuclear modernization program, as well as North Korea’s nuclear weapon and missile programs, are tipping the strategic balance. And third, the nuclear weapons non-proliferation regime—and consequently the restraints against proliferation—have irreversibly weakened. These are all structural factors, not temporary phenomena. They will shape international relations for the foreseeable future.
U.S. President Donald Trump and Japanese Prime Minister Sanae Takaichi arrive at the U.S. naval base in Yokosuka, Japan, on Oct. 28. Andrew Caballero-Reynolds/AFP via Getty Images
It should be obvious to all that the second Trump administration has been extremely disruptive across a number of domains: trade, alliance relations, the war in Ukraine, and others. It seems less committed than its predecessors to upholding what its allies, partners and friends consider the international order. This has caused distress among Washington’s allies, partners, and friends around the world, but perhaps less so in East Asia, which has always dealt with the United States as much—and perhaps more—on the basis of common interests as on common values.
Trump’s changing attitudes to the war in Ukraine have thoroughly unsettled Europeans. But East Asia went through an analogous experience half a century ago, when the United States cut its losses in the Vietnam War and simply left, leaving South Vietnam, royalist Cambodia, and royalist Laos to their fates. A propensity towards unilateralism has always been part of U.S. foreign policy. Remember Richard Nixon’s China shock and his unilateral abandonment of the gold peg for the U.S. dollar? Remember the Plaza Accord? Asian countries work with the United States because they must, and these past shocks have ensured that Asians have generally not used the Americans as a crutch—unlike the Europeans, Canadians, and Australians.
Seen in broad historical perspective, Trump can be described as the first truly post-Cold War president. Since the collapse of the Soviet Union, the United States faces no existential threat anywhere in the world. The dynamics of U.S.-China competition within the global system are fundamentally different from the U.S.-Soviet dynamics of competition between systems, where the clash between capitalism and communism could see only one victor. Competition within a global system is not existential because the goal is not, and by definition cannot be, for one system to replace the other. Beijing may wish to dominate the system and Washington may want to preserve its dominance, but those are not existential goals.
Russia is undoubtedly dangerous and an existential threat to Ukraine and some of the smaller European countries, such as the Baltic states, but not to the United States, where nuclear deterrence will maintain strategic stability. Similarly, North Korea and Iran may pose existential threats to their immediate neighbors, but not to the United States.
Facing no existential threat, there is no longer any reason for Americans—in the words of John F. Kennedy at his 1961 inauguration—to “pay any price, bear any burden … oppose any foe” to defend its ideas of international order. The broad and generous parameters of U.S. strategic interests that Kennedy laid out during the height of the Cold War and that his successors upheld made sense when the United States was facing an existential threat. Does it make sense today? Trump and the millions of Americans who twice voted for him obviously do not think so. For them, it’s time to put “America first.”
There is nothing intrinsically unnatural about this. The world has changed; why should the United States not change? Every country puts itself first. This does not signify a retreat from the world but a unilateral redefinition of the terms of U.S. engagement with the world—a narrower and more transactional definition of national interests. Since this redefinition is a response to a structural factor—the collapse of the Soviet Union and a different type of competition with China—whoever occupies the White House after Trump will adopt much the same approach. The generous definition of U.S. national interests that we had been accustomed to until Trump came along was an artifact of a specific set of historical circumstances that will never return.
How does this affect the nuclear equation in the Indo-Pacific? During his first presidential campaign in 2016, Trump floated the possibility of allowing Japan and South Korea to acquire nuclear weapons as a cheaper way of defending them. We do not know how serious he was, but we should not dismiss it entirely. In any case, U.S. allies should examine the nuclear umbrella of the more transactional contemporary America more carefully.
In his 1994 classic, Diplomacy, Henry Kissinger analyzed how nuclear weapons had changed intra-alliance relations. Before the nuclear age, he argued, “the consequences of abandoning an ally were deemed to be more risky than fulfilling one’s obligations. In the Nuclear Age, this rule no longer necessarily held true; abandoning an ally risked eventual disaster, but resorting to nuclear war at the side of an ally guaranteed immediate catastrophe.”
South Koreans walk past replicas of North Korean missiles at the Korean War Memorial in Seoul on Feb. 28, 2019.Chung Sung-Jun/Getty Images
Japan should think about Kissinger’s cold and clear logic with respect to China’s nuclear modernization program and North Korea’s acquisition of nuclear weapons.
North Korea is now irreversibly a nuclear weapons state. Pyongyang considers nuclear weapons as vital for regime survival and thus an existential issue. There is no cost we can impose or benefit that we can offer that is higher than the cost of abandoning an existential issue. Now that North Korea has nuclear weapons, however few or rudimentary, disarming it by force is no longer an option.
Nor will China help to denuclearize North Korea in any meaningful way. Beijing dislikes Pyongyang’s nuclear weapon program. But since Pyongyang considers nuclear weapons as vital for regime survival, Beijing will never do anything that could jeopardize the survival of a fellow Marxist-Leninist state, one of only five left globally. To Beijing, accepting a nuclear North Korea is a lesser evil.
Therefore, denuclearization of the Korean Peninsula is an impossible dream. That train has left the station. We can now only deal with a nuclear-armed North Korea through diplomacy based on strong deterrence. In his first term, Trump did much to restore deterrence, which had eroded under the Obama administration, and then tried diplomacy, which failed because it set an unrealistic goal of denuclearization. If Trump again tries diplomacy, the only realistic objective would be arms control. That the United States has publicly said in the past that its focus is on North Korean missiles capable of striking the U.S. mainland—not those with a shorter range that can hit Japan—is certainly something Tokyo should ponder.
China is a more important factor in Indo-Pacific nuclear geopolitics. Beijing is upgrading is nuclear arsenal both qualitatively and quantitively. This was overdue since until recently its second-strike capability was relatively rudimentary; certainly it was not in the same league as Russia and the United States. China’s nuclear modernization program suggests that Beijing no longer considers its long-standing policy of minimum deterrence adequate and that it seeks to at least match U.S. deterrence forces.
Of particular relevance is China’s new generation of submarine-launched ballistic missiles (SLBMs), which began to be deployed around 2023. These are the most survivable component of any nuclear arsenal and thus significantly contribute to a credible second-strike capability. China’s new JL-3 has a range of more than 10,000 km and is capable of reaching the continental United States from the South China Sea or Chinese territorial waters in the Bohai Gulf. JL-3s are being deployed on China’s Jin-class nuclear submarines that now undertake continuous deterrence patrols.
This is an extremely significant enhancement of China’s second-strike capability, because the earlier generation of Chinese SLBMs, the JL-2, had a shorter range that required Chinese submarines to pass through the first island chain—which includes Japan, Taiwan, and the Philippines—deeper into the Pacific Ocean. Will the deployment of Chinese SLBMs capable of threatening the U.S. mainland without passing through the first island chain devalue these countries in Washington’s nuclear calculus, and if so, to what extent? It is too early to say definitively. What is clear is that the considerations that established the U.S. defense perimeter in the western Pacific many decades ago are now in flux. It would be prudent not to consider the old perimeter as forever set in stone.
One of the casualties of Russia’s invasion of Ukraine has been the non-proliferation regime. Ukrainian President Volodymyr Zelensky has, on several occasions, expressed regret over his country’s 1994 decision to give up the nuclear weapons inherited from the Soviet Union and instead rely for its security on the paper guarantees of the Budapest Memorandum. It was an act of strategic naiveté. It is unlikely that Ukraine would now be in an existential struggle for national survival if it had retained its nuclear weapons. It is quite clear that the deterrent effect of legal documents is nonexistent when faced with a determined and ruthless adversary. That is why Andrzej Duda, until recently the president of Poland, urged Washington to deploy nuclear weapons on his county’s territory.
The regime determined by Non-Proliferation Treaty was already under stress well before the Ukraine war, and it’s clear that universal nuclear disarmament is a pipe dream. The enormous destructive power of nuclear weapons and the great strategic advantage a nuclear weapons state has over an adversary armed only with conventional weapons creates a prisoner’s dilemma that is well-nigh insurmountable. Although everyone would theoretically benefit from a world without nuclear weapons, the risk of an adversary cheating is just too high to take.
Whether we like it or not, nuclear weapons are here to stay. In a nuclear world, stability can ultimately only be maintained by deterrence through mutually assured destruction (MAD). There is no alternative. As the noted U.S. scholar Robert Jervis pointed out, MAD is not a policy choice but a description of reality. It is even better described as an existential reality and therefore now part of the human condition.
Visitors to the Hiroshima Peace Memorial Museum view a panoramic photo of the aftermath of the atomic bomb attack on Hiroshima in 1945, seen in Hiroshima on Aug. 5, 2020.Carl Court/Getty Images
In summary, irreversible structural factors will inexorably weaken U.S. extended deterrence over time. The shelf life of the nuclear umbrella can be extended; ideas like bilateral nuclear sharing or the reintroduction of U.S. tactical nuclear weapons are being tentatively floated. But the shelf life of extended deterrence cannot be prolonged indefinitely.
The crucial question confronting Northeast Asia—which, when one adds Russia to China and North Korea, already contains three nuclear weapons states that are not particularly friendly to Japan or South Korea—is whether such a state can be deterred by conventional means. The corollary to this question is whether Washington will sacrifice Los Angeles or San Francisco to save Tokyo or Seoul.
These are not questions that the Japanese (and South Koreans) need to answer right away, but they cannot be indefinitely avoided without grievous risk. They are very difficult and politically fraught questions, but that is precisely why there is an urgent need for a frank, open, and realistic discussion. The conclusions eventually reached will have profound implications for Japan’s future and that of the region.
Much is at stake, but the main risk is not a cataclysmic war. Such a risk is an inherent characteristic of international relations and therefore never entirely absent, but in my view, it is not very probable. The more probable and more invidious risk is that, as the credibility of U.S. extended deterrence erodes, there will be a long and slow degradation of Japan’s autonomy by a series of almost imperceptible steps, each justified as a reasonable compromise to avoid confrontation with a nuclear-armed neighbor. The end result will be a Japan that still exists as a separate polity but is something less than fully sovereign. The most relevant neighbor in this scenario is obviously China.
This would in effect reverse the trajectory of more than four centuries of Japanese history. Ever since Toyotomi Hideyoshi unified Japan in 1590 and invaded Korea two years later, a very large part of Japanese identity has been defined by a refusal to be subordinated to the Sinosphere. As seen by its friends in the region, a Japan that is something less than fully sovereign cannot play the bigger and more proactive role in maintaining the equilibrium in a shared region, supporting and supplementing a United States that now defines its interests more narrowly. Although only the Japanese should decide Japan’s nuclear future, the consequences of their decision could determine the balance of power in Asia.
This article is an adapted excerpt of a speech given at the Kajima Institute of International Peace in Tokyo on Oct. 16.