In September 2015, a major Military Parade was held at Tiananmen Square in Beijing to mark the 70th Anniversary of China’s victory in the 1937-1945 war with Japan.

Among guests at the viewing deck was then South Korean President Park Geun-hye, side by side with Russian President Vladimir Putin and Chinese President Xi Jinping, presenting a shocking scene to Japan and the United States.

Park attended the event despite calls from Tokyo and Washington for her to refrain from doing so.

While Japan and the United States are increasingly wary of China’s ambitions to expand its influence in the Pacific region, South Korea’s attitude toward China still tends to waver as a result of its economic reliance on the country.

South Korea has not ruled out cooperating with China’s Belt & Road Initiative, while also supporting the vision of a Free and Open Indo-Pacific region sponsored by Japan and the United States.

Trilateral cooperation among Japan, the United States and South Korea is a product of the Cold War and three decades after the conflict ended, the tripartite framework is being tested as China’s growing military and economic power is changing the geopolitical game around the Korean Peninsula.

Since Park’s successor, Moon Jae-in, took office in 2017, the relationship between Japan and South Korea has deteriorated to what many see as the lowest point for bilateral ties since the end of World War II.

While promoting efforts for reconciliation with North Korea, the Moon administration is fiercely at odds with the Japanese government over history and trade issues. The escalating tension is annoying Washington, which serves as the pivot of the three-way framework of cooperation based on the Japan-U.S. and U.S.-South Korea security alliances.

In particular, the U.S. government has expressed disappointment over South Korea’s unilateral decision last month to end its military information-sharing agreement with Japan.

The United States is also increasingly frustrated with the Moon administration’s self-proclaimed role as a mediator between the United States and North Korea.

After U.S. President Donald Trump and North Korean leader Kim Jong Un failed to reach an accord during their second round of talks in February, the United States cancelled a two-plus-two session between its Foreign and defence chiefs and their South Korean counterparts, which was set for April.

And talks between Trump and Moon at the White House in mid-April were cut extremely short.

A U.S. government official said South Korea should stand on the U.S. side, rather than act as a mediator. Another official said a sense of distrust in the Moon administration is growing within the U.S. government.

A former senior South Korean military officer accused the Moon administration of taking advantage of anti-Japan sentiment among South Koreans to push ahead with his political agenda.

South Korea is in diplomatic deadlock now, the former officer pointed out, referring to growing antipathy among South Koreans toward the U.S. government, which is pressing South Korea to shoulder much more of the costs of the U.S. military presence there, as well as the people’s discomfort with China’s heavy-handed attitude.

Japan, the United States and South Korea share a strategic interest in stable regional development on a basic level, another U.S. government official said.

However, if the three countries prioritise their respective domestic politics over the shared regional interests, trilateral cooperation could fall apart, which would be a boon for China, the U.S. official warned.

Editor’s note: The article reflects the author’s opinion only, and not necessarily the views of editorial opinion of Belt & Road News.