The United States deterrence capability would certainly increase with the redeployment of its Practically, states with low power capabilities ally themselves with major powers to balance a threat. Sometimes, this security umbrella is provided by the major powers they, or the smaller states ask for it. Japan and South Korea, in the East Asian security complex, are currently under the US nuclear umbrella, which means they rely on the US for their security against threats emerging from the evolving regional order. The arrangement has been in place for decades and has been a cornerstone of US alliances with Japan and South Korea. In the post-World War II era, Yoshida Doctrine spurred US security aegis as Japan wanted to focus more on its economy. In 1967, PM Sato also established nuclear principles as “no possession, introduction or production”. It restricted Japan to produce its nuclear capabilities and the US to shift any nuclear device to its bases in the country. Relatively, the Extended Deterrence Strategy that assures that the US will use specific military assets including nuclear weapons against threats to South Korea backs the US’s commitments to South Korea’s security.

Japan and South Korea, in the East Asian security complex, are currently under the US nuclear umbrella, which means they rely on the US for their security against threats emerging from the evolving regional order.

However, there have been reports; Japan and South Korea are beginning to consider developing their nuclear weapons in response to China and North Korea’s growing military power. Some members of the international community fear that this could start a regional arms race and may have destabilizing effects on the region.

The possible reasons for the nuclearization of Japan and South Korea are complex and multifaceted, but some of the main factors driving the debate include the following:

1. North Korea has been developing its nuclear weapons program for several years and has conducted several missile tests, raising concerns about its intentions and potential threat to the region. Both Japan and South Korea are within range of North Korean missiles, and could therefore feel particularly vulnerable to a potential attack. The possibility of nuclear weapons in the hands of North Korea is forcing Japan and South Korea to consider nuclearization to enhance their security.
2. China’s military expansion and aggression in the region have raised some concerns in Japan and South Korea about the possibility of a future confrontation with China. The Chinese government also has territorial claims in the South China Sea, which are also claimed by other countries, including Japan and South Korea. Thus, the possibility of a confrontation with China may force Japan and South Korea to consider nuclearization as a means of enhancing their deterrence capabilities.

The US has been a key ally of both Japan and South Korea and has provided both countries with a nuclear umbrella. However, there are concerns about the credibility of the US security commitment, particularly under the current US administration.

East Asian policymakers and the public have good reason to believe that the ongoing conflict between Ukraine and Russia will deter the United States from taking direct military action against nuclear-armed states like Russia to prevent nuclear war.

It is well known that US President Joe Biden ruled out the use of US armed forces in the initial phase of a Russian invasion in 2022. He has repeatedly pledged not to send US troops to Ukraine. Thus, Japan and South Korea are considering nuclearization as a means of increasing their security and reducing their dependence on the United States. There may also be domestic political considerations driving the debate around the nuclearization of South Korea. There is a long debate in Japan about the country’s pacifist constitution and reliance on the US for security. There is growing debate in South Korea about the country’s military capabilities and its ability to defend itself in the face of potential threats.

Implications for China:

If Japan and South Korea acquire nuclear weapons, it will create a new nuclear balance in the region, with the possibility of a nuclear arms race. This could increase tensions and instability in the region, and China could increase its nuclear arsenal in response. Nuclearization in South Korea and Japan could weaken China’s strategic edge and regional influence.

A nuclear-armed Japan and South Korea would weaken China’s regional power and might prompt a more aggressive response from China, which is attempting to expand its influence in the region.

China might see a direct danger to its security from Japan and South Korea going nuclear. This might cause China to adopt a more combative and aggressive attitude, which might eventually result in a military conflict. The development of nuclear weapons in Japan and South Korea would have a significant impact on China’s regional power and strategic considerations, as well as raise regional tensions and instability.

Implications for the South China Sea:

The development of nuclear weapons in Japan and South Korea may result in a rise in militarization and resource rivalry in the South China Sea, which could spark conflicts and can further destabilize the area. International politics in the South China Sea region may be impacted by Japan and South Korea going nuclear. The region’s smaller countries have already accused China of bullying, and the creation of nuclear weapons by South Korea and Japan could make matters more difficult diplomatically. Other nations in the region, like Vietnam and the Philippines, might be compelled to choose a position, which could result in a more polarized regional situation.

Implications for the US:

The nuclearization of South Korea and Japan would diplomatically weaken ties between the US and both states. Since the United States has long promoted nuclear disarmament and non-proliferation, the development of nuclear weapons by Japan and South Korea would be viewed as a failure of American foreign policy. Security-wise, the nuclearization of South Korea and Japan could lead to an uptick in regional tensions and a new arms race. This would increase the probability of a nuclear conflict and directly risk the security of the United States and its allies. Furthermore, the spread of nuclear weapons in Asia may raise the possibility of nuclear terrorism, which would be of great concern to the US.

Tactical nuclear weapons in South Korea, but would also increase tensions with China and North Korea and increase the chance of a nuclear exchange on the Korean Peninsula. Further destabilizing the area and weakening global non-proliferation efforts could be nuclear sharing agreements or South Korea’s acquisition of nuclear weapons capability.

Conclusion:

It is the ultimate goal of any state to make itself secure in any given situation by relying less on other states and depending on itself more, Japan and South Korea are also doing the same thing. The development of nuclear weapons by Japan and South Korea would have profound and far-reaching effects on regional and global security, diplomacy, military tactics, economic ties, and non-proliferation programs. These developments would require the USA to reconsider its defense and foreign policy tactics in the region and might result in an uptick in hostilities between the US and China and Russia. Additionally, it might cause an arms race in the region, which will develop more unrest and a direct security danger to China as well. If Japan and South Korea go nuclear then it surely will boost the arms race in the region including the South China Sea.