Japan needs nuclear weapons. Surrounded by authoritarian threats, including Russia, China, and China’s close ally, North Korea, Japan would make all democracies safer by protecting itself with a nuclear weapon. A stronger Japan will check China’s expansion and free U.S. military resources for deployment elsewhere.
In this Aug. 28, 2014 photo, a Chinese nuclear submarine sails past fishermen of Yalong Bay in Sanya, south China's Hainan Province. Several Asian nations are arming up, their wary eyes fixed squarely on one country: a resurgent China that’s aggressively asserting territorial claims all along the East Asian coast. The scramble to spend more defense dollars comes amid spats with China over contested reefs and waters. AP Photo/Andy Wong
Japan supposedly enjoys protection from an American “nuclear umbrella”. But Japanese leaders are unsure that the U.S. would come to its defense in a major war, much less a nuclear war. Russian, Chinese, and possibly even North Korean missiles can deliver nuclear weapons to the U.S., its territories, and its military bases in Asia. North Korea could even put a nuclear weapon in a cargo container and ship it to a U.S. mainland port. In defense of Japan, would the U.S. really strike a major conventional or even nuclear blow against the military forces of one of these authoritarian states, and thereby risk a cold-hearted nuclear counter-attack against Honolulu, San Francisco, New York, or Washington, DC? Such a counter-attack could destroy the U.S. economy for decades, cause a fiscal crisis that would mean decreased military expenditures and military retreat from U.S. forward-deployed positions, and kill millions of Americans.
Military and diplomatic analysts in Japan are increasingly unsure that Washington would take this risk after Japan itself may have suffered a conventional or nuclear blow that devastates its military strength as an ally. If Japan questions the willingness of the U.S. to counterstrike a nuclear-armed adversary, then Russia, China, and North Korea are likely questioning Washington’s commitment as well. They may see the current lack of commitment as an opportunity for a preemptive conventional or nuclear strike against Japan’s military. This is not a safe position for any country to be in, especially a country like Japan whose military forces are daily threatened by the aggressive nuclear and other brinkmanship of these same adversaries.
Because Russia, China, and North Korea may perceive a lack of U.S. commitment, Japan needs an iron-clad nuclear deterrent force. There is no better such deterrent than one that Japan would own and control itself, coupled with a public announcement to reserve the option of using that deterrent force against any state that attacks it or infringes its sovereignty. This is a far stronger and more reliable nuclear deterrent than the current U.S. umbrella.
Some have argued that a Japanese nuclear weapon would cause China or North Korea to attack Japan militarily. They are wrong. Once Japan goes nuclear, China and North Korea cannot attack without factoring in the risk of a devastating nuclear counter-blow. A Japanese nuclear deterrent would also decrease worries in Japan that China dominates the upper rungs of the escalation ladder theorized by Herman Kahn. Japan’s conventional military, combined with an indigenous nuclear deterrent and its strong U.S. alliance, would thereby have far more latitude to stop Chinese, Russian, and North Korean attacks and blustering.
Economic retaliation for a Japanese deterrent is also likely to be light. President Trump has already positively raised the idea of a Japanese nuclear deterrent. It is unlikely that Japan would suffer U.S. or unilateral European economic sanctions. 
China exports more to Japan than Japan exports to China. If China wants to proceed down a road of economic tit-for-tat, as much pain could be done to China as vice versa. If the U.S. supports Japan with retaliatory economic sanctions against China, the economic cost to China would devastate its economy and thereby destabilize the government. The stability of the government is perhaps Xi Jinping’s greatest goal, so China will not invite economic disaster by imposing economic sanctions on Japan.
Some argue that a nuclear Japan will increase pressure on the Non-proliferation Treaty (NPT). But, the NPT has been a failure for Asian democracies. China, Russia, and North Korea have nuclear weapons, and they are aggressively bullying the region. The reasonable democracies have followed the rules, and as a result are now at risk of war because of these authoritarians’ constant threats against territorial features like the Senkaku Islands. Given that territorial expansion seems to be the mindset of leaders in Russia, China, and North Korea, democracies must defend themselves. Japan cannot continue to risk its sovereignty because of its very well-intended and understandable pacifism. It needs to recognize the reality of increasing Chinese, North Korean, and Russian militarism, and it needs to defend itself with an unquestionable nuclear deterrent.
U.S. security is improved when stable democracies like the UK, France, and India have obtained a nuclear deterrent. It keeps them safe from their enemies, and through our alliances, strengthens the U.S. Yet when the UK, France, and India initially developed nuclear deterrence in 1952, 1960, and 1974 respectively, the U.S. was not fully cooperative. We now have the benefit of close security cooperation with these strong nuclear democracies, which act as important counterweights against Russia and China. Their nuclear deterrents allow them to forward deploy their forces for global peacekeeping, and against piracy and terrorists, while at the same time remaining unintimidated by authoritarian regimes. 
Germany, Poland and South Korea should also obtain nuclear weapons. These frontline regional powers need them as a deterrent against authoritarians, war and regional instability. The threat of war is real, given China’s violation of Philippine sovereignty with the occupation of Mischief Reef in 1995, and Russia’s occupation of Ukraine in 2014. These two occupations, which still go militarily unchallenged, instantiate an unfortunate lack of resolve by the United States to back up its obligations to the Philippines per the Mutual Defense Treaty of 1951, and to Ukraine under the Budapest Agreement of 1994. It is precisely because the U.S. did little to defend these countries when arguably obligated to do so by solemn agreements, that Japan now questions U.S. resolve to risk nuclear war to defend Japan from China, Russia, or North Korea. 
If Japan goes nuclear, it will not cause non-nuclear authoritarian countries to do the same. While some countries like China and North Korea hype a threat from Japan in their state-run media, no serious analysts see Japan as an aggressive power. It is a democracy with a pacifist constitution. It has experienced the horrors of nuclear war as has no other country. Vietnam, for example, will not see a Japanese nuclear weapon as a threat. Rather, it will see a Japanese nuclear weapon as stabilizing Asia through a check on China, Vietnam’s main threat. Such a weapon could even allow Japan to increase economic and military aid to Vietnam in the safety of knowing that China would be less likely to retaliate.
Australia, South Korea and Taiwan might go nuclear, but not from fear of Japan. In fact, Japan’s going nuclear might decrease the probability of these countries going nuclear because they would feel safer with Japan’s new nuclear check on China. If they did go nuclear, however, they would be additional bulwarks against authoritarian aggression in Asia and thereby increase stability in the region. They are well-developed democracies that would maintain security procedures such that nuclear weapons did not fall into the hands of extremists. As responsible democracies, they can be counted on to only maintain their nuclear deterrent for defensive purposes.
Asian democracies should not allow the authoritarian nuclear powers of the world to bully them. Asia would be more stable if front-line states against China had nuclear weapons. None of these countries are likely to go to war with each other, so the simplistic mathematical argument that ‘the more countries that have nuclear weapons, the more likely is a nuclear war,’ does not apply. Democracies are not like autocracies. They are defensive in orientation. The democratic peace theory has been proven: democracies do not fight each other.
Could the nuclearization of Asian democracies lead to nuclear proliferation in authoritarian regimes beyond Asia, for example in the Middle East? It is possible that Iran and Saudi Arabia, which are currently involved in multiple proxy wars, would use Asia’s nuclearization as an excuse to go nuclear themselves. However, even with Israel’s nuclearization, these countries have thus far been restrained by the threat of economic sanctions and diplomatic ostracization. They are authoritarian regimes, which history shows us are known to be aggressive against democracies. Until they democratize, they should not be trusted with nuclear weapons. The added strength that the democracy club of countries would have through additional nuclear members will be sufficient to free political and economic resources to pressure authoritarian regimes from going nuclear. 
Last year, Vice President Joseph Biden told Chinese President Xi Jinping that Japan can go nuclear ‘virtually overnight’. President Trump has a strongly adversarial relationship with China, and said, “If the United States keeps on its path, its current path of weakness, [Japan and South Korea] are going to want to have [a nuclear deterrent] anyway with or without me discussing it.”