Russia’s invasion of Ukraine in February 2022 has had significant ripple effects on the United States’ allies in the Indo-Pacific. Both Tokyo and Seoul are now asking Washington to be more engaged in the region, with Japanese Prime Minister Fumio Kishida warning in January 2023 that “Ukraine today may be Asia tomorrow.”
The South Korean nuclear discourse seems to have taken a particularly sharp turn since the war in Ukraine started. A February 2022 survey by the Chicago Council on Global Affairs and the Carnegie Endowment for International Peace showed that 71 percent of South Korean respondents supported their country developing nuclear weapons and 56 percent favored the return of US tactical nuclear weapons to the peninsula. This shift in public sentiment was echoed by South Korean President Yoon Suk Yeol. Speaking during a policy briefing in January, he stated that if North Korea’s nuclear threat continues to grow, South Korea might consider building its own nuclear weapons or asking the United States to redeploy tactical nuclear weapons on the Korean Peninsula. President Yoon did try to explain a few days later that his comment was not to be taken as an official policy change, but it came too late: His gaffe had already made a loud impact in the news.
Yoon’s January comment was the first time since the early 1990s, when the United States withdrew its nuclear weapons from the peninsula, that a South Korean president shared such thoughts publicly. Most recently, Seoul Mayor Oh Se Hoon doubled down on the idea, calling for South Korea’s nuclearization during a March media interview. As Carnegie senior fellow Toby Dalton puts it, South Korea “is exhibit A” for recent developments in the international security environment, including Russia’s invasion of Ukraine, China’s rapid military buildup, and North Korea’s mounting provocations.
These recent comments about nuclearization in South Korea may have raised decades-old doubts in Washington about the potential of a classic regional nuclear domino effect: If Seoul goes nuclear, will Tokyo follow suit?
Japan as the “deterrence-fluent ally.” Recent debates about nuclear weapons in Tokyo have been much more contained than in Seoul. Immediately after Russia’s invasion of Ukraine in late February 2022, former Prime Minister Shinzo Abe explicitly suggested on television that Japan should consider a NATO-style nuclear-sharing arrangement. Current Prime Minister Fumio Kishida, however, is more dovish than most of his fellow Liberal Democratic Party members and quickly shot down the idea, calling it “unacceptable.” At least one other former Japanese official also mentioned the importance of debating a nuclear-sharing agreement with the United States since the war in Ukraine began, but there has been no noticeable change in the Japanese government’s nuclear rhetoric or in the public’s attitude.
As neighbors, South Korea and Japan face similar regional threats and are both long-time US allies. But they see their national security in the region slightly differently: South Korea’s main concern remains North Korea, while Japan focuses on China as its main threat. Although Japan’s official stance towards Taiwan and Beijing has not changed, the Russian invasion of Ukraine made Tokyo more vocal and serious about deterring a potential forceful change of status quo by Beijing. Japan is still convinced that China will not abandon its ambitions on Taiwan, and Japan’s new National Security Strategy, released in December 2022, describes China’s current stance as “a matter of serious concern” and “an unprecedented and the greatest strategic challenge.” Prominent political figures in Japan have also recently stated that a Taiwan contingency is a contingency for Tokyo.
Source : The Bulletin