South Koreans, Japanese support stronger mutual security cooperation

Marking the 60th anniversary of normalized diplomatic relations, a joint public opinion survey by The Dong-A Ilbo and The Asahi Shimbun found growing public support in South Korea and Japan for closer security cooperation. The results reflect mounting concern over regional instability, including deepening ties among North Korea, China, and Russia, and suggest that the two countries, as Asia’s leading democracies, are increasingly aligned in seeking a coordinated response.

When asked whether defense cooperation should be strengthened, 60 percent of South Koreans and 56 percent of Japanese respondents said yes. In South Korea, where such collaboration has historically been sensitive due to Japan’s colonial past and the ongoing Dokdo territorial dispute, the data indicate growing support for practical security coordination. Backing for stronger ties surpassed 50 percent across all age groups and genders. Among South Koreans aged 18 to 29, 68 percent were in favor, while 67 percent of those aged 70 and older also supported increased cooperation. By gender, 61 percent of men and 57 percent of women agreed.

A similar pattern emerged in Japan, where every age group showed majority support. The highest approval came from respondents in their 20s at 60 percent. Among men, 59 percent supported closer defense ties, compared with 53 percent of women.

Historically, military cooperation between South Korea and Japan has been politically sensitive. In 2019, the Moon Jae-in administration announced plans to exit the General Security of Military Information Agreement, or GSOMIA, in response to Japan’s export restrictions on semiconductor materials. Although the decision was later reversed, the episode highlighted how contentious bilateral security ties have been. Today, however, more South Koreans see cooperation with Japan as a necessary strategic choice.

The shift may be partly driven by rising anxiety over North Korea’s advancing nuclear weapons program. When asked about their concerns over the North’s nuclear development, 52 percent of South Koreans said they were either “very anxious” (25 percent) or “somewhat anxious” (27 percent). In Japan, 82 percent expressed worry, split evenly between “very anxious” and “somewhat anxious.” The results reflect deepening unease following the collapse of U.S.-North Korea nuclear talks during the first Trump administration and North Korea’s ongoing weapons advancements.

In a separate question asked only in South Korea, 58 percent said defense cooperation with Japan should be strengthened amid growing ties among North Korea, China, and Russia. Another 30 percent said the current level was sufficient, 9 percent favored reducing cooperation, and 3 percent had no opinion.

The findings come as North Korea reportedly deployed 11,000 troops to support Russia in the war in Ukraine, signaling a deepening military alliance. Meanwhile, China has expanded its nuclear arsenal by about 100 warheads annually since 2023. These developments appear to be driving renewed public support in South Korea for stronger security ties with Japan.


In-Chan Hwang hic@donga.com