Joseph Yi is an associate professor of political science at Hanyang University in Seoul. South Korea's nuclear debate has moved to the political spotlight.

On Aug. 16, Donald Trump ordered the Pentagon to "substantially" reduce joint military exercises with South Korea citing their cost, his relationship with North Korean leader Kim Jong-un and Seoul's refusal to join U.S. action against Iran. Days later, Washington and Seoul cut short the annual Ulchi Freedom Shield exercise and reduced field training.

South Korean politicians Na Kyung-won, Yoon Sang-hyun and Ahn Cheol-soo called for an independent nuclear capability or a national debate over it. Public support is broad but conditional.

The Korea Institute for National Unification (KINU) found 68% favored independent nuclear armament. Still, support fell to 47.7% if sanctions could trigger an economic crisis and 45.7% if nuclear development risked the U.S. terminating the South Korea-U.S. alliance and withdrawing its troops from the country. The Asan Institute for Policy Studies reported 80% baseline support, falling to 63% with international sanctions and 52.2% with possible U.S. troop withdrawal. That caution is rational.

Unilateral withdrawal from the Nuclear Non-Proliferation Treaty does not trigger automatic sanctions but risks nuclear cooperation, access to technology and alliance support. The 2026 Korea Economic Institute of America (KEI) survey conducted with YouGov found that 71% of Americans opposed Seoul developing nuclear weapons. The Japan-South Korea Joint Opinion Poll by the International House of Japan (IHJ) and the East Asia Institute (EAI) in South Korea found 57.4% of Japanese respondents opposed.

Nuclear unilateralism resembles Trump-style populist politics: distrusting institutions, questioning long-standing commitments and promising greater security through unilateral strength.

South Korea derives its influence from the opposite strategy. It is prosperous, technologically important, internationally connected and predictable. Its security depends not only on military capabilities but on a dense network of countries that benefit from South Korea's success.

In today's economy, countries that leverage openness, human capital and international relationships are better positioned to become leading nodes of AI development and supply chains. Decisions made now shape investment, productivity and opportunity for decades. Instead of seeking nuclear armament, South Korea should become an essential technological partner to the United States, Japan, China and other major economies.

This strategy is already visible in semiconductors. SK Hynix, which is central to the AI supply chain through high-bandwidth memory, is building advanced AI-chip capacity in Indiana while retaining major manufacturing and commercial interests in China. These overlapping relationships are an asset.

Over-securitizing economic relationships carries costs: fewer suppliers, higher compliance burdens, reduced flexibility and weaker incentives for cross-border investment. The U.S. restrictions already complicate South Korean semiconductor operations in China, prompting South Korean companies to test Chinese equipment as a hedge against uncertainty over access to U.S. tools. Security controls are sometimes necessary, but treating every technological relationship as geopolitical rivalry increases costs for companies and consumers.

South Korea's long-term objective should be to remain a trusted U.S. ally while also serving as a principled and commercially attractive partner for China and other economies. The more countries depend on South Korean manufacturing and memory chips, the more costly it becomes to marginalize South Korea. Strategic indispensability creates leverage of its own.

Japan lacks comparable public demand for an independent nuclear arsenal, with 49.9% of survey respondents opposed and 29.9% favoring, according to the IHJ-EAI poll.

Like South Korea, Japan gains more from technological indispensability than nuclear nationalism. Japanese companies remain crucial suppliers of semiconductor materials and equipment. Recently, Kioxia and Sandisk have announced plans to invest more than $31 billion in Japanese memory production.

South Korea and Japan therefore share a strategic interest: becoming countries that others value as trusted technological and economic partners. Doing so requires openness to capital, talent, technology and markets from multiple sources, including from each other.

This does not mean neglecting deterrence. After North Korea's Oct. 3 hypersonic missile drill, President Lee on Oct. 8 oversaw South Korea's first test of a domestically developed hypersonic missile. His administration is also investing in AI-based missile defense and high-powered laser interceptors.

The U.S.-ROK Korea Nuclear Consultative Group provides mechanisms for nuclear-crisis consultation, conventional-nuclear integration, exercises, training and information sharing.

Strategic circumstances can change over time. If independent nuclear weapons eventually become necessary, Seoul should pursue such a fundamental strategic shift in coordination with its democratic allies.

The lesson of the Trump era is that not every country should imitate Trump. For middle powers, unilateralism risks the institutions, relationships and reputational assets that sustain both security and prosperity. South Korea and Japan benefit more from democratic reliability, technological centrality and global integration than from nuclear populism.