Skand Tayal | Will Trump's United States unilaterally bring Japan and South Korea to “nuclearization”?

The unpredictable foreign policy of the Trump administration in its first 100 days has introduced uneasiness among other NATO members about the reliability of U.S. security guarantees. In the Indo-Pacific, the United States' major defense allies are Japan, South Korea and Australia. Japan and South Korea face direct threats from North Korea's nuclear weapons, as well as indirect threats from North Korea's security provider China.

Despite the continuous U.S. government assured Japan and South Korea that its nuclear umbrella to its allies is “Ironclad,” Donald Trump’s recent actions in actually giving up Ukraine’s own destiny could force two strategists in Northeast Asia’s democracies wondering if a future U.S. president would be ready to attack California in order to save Tokyo or as well-known.

This uncertainty has survival significance for decision makers in Japan and South Korea. As global strategic forces turn to the Indo-Pacific, China tries to rule the region,

Japan is oppressed between two contradictory orders: based on pacifism and nuclear constraints on regional insecurity and post-war identity. Competition between the United States and China, North Korea’s Moyu behavior and the fate of non-nuclear countries such as Iraq, Libya, Syria and Ukraine may spark debate over whether Japan should map its own nuclear process.

Regional security environment has turned dark since President Xi Jinping consolidated his power over the past decade. China's confidence has gone beyond the scope of economic coercion, such as restrictions on Japan's rare earth minerals for tough military postures. Beijing's naval presence near the Senkaku Islands in Japan, on-site fire drills near Taiwan and the booming blue water naval signal is a kind of state that provides territorial expansion for force. Meanwhile, North Korea's continued missile testing and relentless nuclear development have exacerbated the threats facing Japan and South Korea. More complicated is the breakdown of international rules and orders reflected by Beijing’s reflection on UNCLOS in the South China Sea and Russia’s “special military operations” against Ukraine.

In this fluctuation, the credibility of the cornerstone of Japan's security expands its deterrence will certainly be under scrutiny. The Trump administration's attitude toward the coalition's deal and public thoughts on the withdrawal of troops have become suspicious in Tokyo. Although the Biden administration has taken action to strengthen the alliance structure, the ghost of returning to American isolationism has once again raised questions about Japan’s ability to rely on others to defend.

Despite this uncertainty, nuclearization is still politically unpopular in Japan. Former Prime Minister Fumio Kishida, a Hiroshima native, reiterated that Japan adheres to its three non-nuclear principles: not owning, making or allowing the introduction of nuclear weapons. Even conservative analysts, who advocate revising Japan's constitution, expanding the definition of “self-defense” and increasing the definition of military budget, have stopped calling for indigenous nuclear weapons.

The dominant aspect is testing the boundaries of the Japanese pacifist constitution – doubled the defense budget and gained the ability to strike remotely – but it did not venture into nuclear territory.

Tokyo's response to deterioration in the Indo-Pacific security environment in the face of expansionist China's expansionist China is powerful, but not nuclear. This is a national security strategy, and the 2024 Defense White Paper marks a decisive shift toward strengthening its defensive posture. Gain counter-war capabilities and enhance missile defense and operation new areas such as cyber and space. Become a powerful conventional military force without giving up its anti-nuclear commitment.

But this sentiment may change, just as India has changed. Japan has the technical ability to build nuclear weapons. Its advanced civilian nuclear infrastructure, scientific foundations and delivery capabilities place it in the world's most prepared non-nuclear countries. Under the 1987 civil nuclear cooperation agreement with the United States, Japan could add more aggressive fuel to spend from its civil nuclear reactors. Therefore, it has a p-bird library that can be transferred to form a p-bomb.

On the other side of the East China Sea, South Korean policymakers have debated its nuclearization for decades as a response to North Korea’s irreversible and evolving nuclear weapons program and delivery system.

In January 2023, former President Yoon Suk-Yeol said that if provocations in Pyongyang intensified, “our country may introduce tactical nuclear weapons or build them themselves”.

In response to this nuclear pro-notic sentiment, the United States signed the Washington United States-Washington Declaration in April 2023, strengthening cooperation on nuclear deterrence through more consultations on strategic nuclear affairs. But this is under the leadership of the Biden administration.

Despite witnessing an unprecedented melting of relations between the two North Koreas on 2018-19, North Korean rhetoric has now become strong. In October 2024, North Korea revised its constitution, declared South Korea a “hostile country” and abandoned its long-term policy of “unification” with South Korea.

Part of this complex riddle is the continued refusal of the United States to allow South Korea to reprocess its used nuclear fuel from nuclear power plants. South Korea's defender is subject to further negotiations with the United States under the 2015 “Peaceful Nuclear Cooperation Agreement”. South Korea has huge reserves with highly dangerous fuel on it. Its ambassador reportedly said in October 2024 that it would discuss the issue with the upcoming U.S. government.

It depends largely on the future strategy of the Trump administration. President Trump advocates “burden sharing” with his allies and encourages regional powers to take more responsibility for themselves and regional security. But what are the limitations of this method? The US guarantee changes every four or eight years. How reliable is the US guarantee? Tokyo and Seoul need to think about these uncertainties to solve this existing problem.