South Korea

It's complicated. South Korea-Japan shows solid military and diplomatic alignment — both are US treaty allies cooperating on North Korean missile defence — but regime relations and societal relations remain weighed down by unresolved WWII-era grievances including forced labour and comfort women disputes. Notably, South Korea-Australia scores higher on military cooperation despite being geographically distant, showing how history constrains what should be a natural alliance.

North Korea is South Korea's most hostile relationship by a wide margin — deeply negative across military, diplomatic, regime relations, and societal dimensions. It is the single deepest rivalry in the dataset for either country. The next-worst relationship (Russia) is far less hostile. These scores reflect the technically ongoing state of war, Pyongyang's nuclear arsenal aimed at Seoul, and the complete ideological and societal separation between the two Koreas.

Under President Lee Jae-myung, the alliance shifted from passive reliance to transactional partnership. Diplomatic alignment is the highest for any South Korean bilateral relationship, reflecting the landmark investment deal and nuclear submarine negotiations. However, regime relations lags behind — lower than South Korea-UK or South Korea-Germany — hinting at friction over 'America First' protectionism and wartime operational control transfer.

South Korea-China scores are negative across the board. The military dimension is the most hostile, reflecting China's opposition to THAAD missile defence deployment and its close ties with Pyongyang. But diplomatic and regime relations are milder than many Western countries' China scores, reflecting Seoul's careful calibration to avoid provoking its largest trading partner while maintaining its security alliance with Washington.

After the United States, South Korea's top allies are Germany, Australia, the United Kingdom, and the Philippines. This list reveals a country with a diversified, globally-oriented alliance network. Australia shows strong military cooperation reflecting joint exercises and arms deals, while the Philippines partnership is driven by shared concerns over Chinese maritime assertiveness in the South China Sea.

Yes, and the scores reflect this pivot. South Korea's military alignment with non-US partners is increasingly strong across Australia, the Philippines, Japan, Germany, and the UK. The push for nuclear-powered submarines, wartime operational control transfer, and domestic defence industry expansion (K2 tanks, KF-21 fighters for export) all signal a country moving from a defended outpost to a sovereign military power.

South Korea's US military alignment is strong but notably lower than Japan-US or Australia-US equivalents in most assessments. Where Seoul stands out is diplomatic alignment — the highest of any bilateral relationship for South Korea. The regime relations gap between the US and the UK captures an interesting tension: South Korea's democratic values align more naturally with European sensibilities than with Trump-era American populism, even as its security depends overwhelmingly on Washington.

South Korea-India shows a steady, growing partnership that hasn't yet reached major ally status, with moderate positive alignment across all dimensions. For context, India scores higher diplomatically with the UK and France, suggesting Seoul has room to deepen this relationship. Both nations share concerns about Chinese assertiveness, creating a natural foundation for closer security cooperation in the Indo-Pacific.