Is the threat of North Korea spurring Japan-South Korea rapprochement?

Leaders of Japan and South Korea have met at a summit to boost bilateral relations in areas such as economy, security, and communication after 12 years of diplomatic tensions between the two countries.

Japanese Prime Minister Fumio Kishida and South Korean President Yoon Suk Yeol highlighted the need for solidarity, saying that they hope to resume regular visits after their bitter history dating back over 100 years.

Seoul and Tokyo share similar concerns about North Korea and China, which has pushed the two US allies towards a diplomatic thaw in relations.

North Korea launched a missile early Thursday, shortly before the South Korean president departed for Tokyo. The intercontinental ballistic missile was encountered between Japanese and Chinese vessels in disputed waters and fell into open waters off Japan's northern island of Hokkaido.

The timing of the North Korean missile triggered thoughts on whether it was a threatening message to the two US allies who were about to meet to strengthen ties.

The two leaders called for cooperation and solidarity, conveying that the North Korean threat was an underlying reason for better bilateral relations.

"The need to strengthen South Korea-Japan cooperation has never been greater in the era of complex crises, brought by uncertainties in global geopolitics, North Korea's continued nuclear and missile testing activity and the disruption in industrial supply chains," South Korean Vice Foreign Minister Cho Hyundong said last week.

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US-South Korea joint drills

The growing threat of Pyongyang missiles seems to have been stimulating the East Asian countries' partnerships with the US and each other. Last October, North Korea fired an intermediate-range missile over northern Japan, causing communities to issue evacuation alerts and halt trains.

The South Korean and US militaries recently launched "Freedom Shield exercises", their largest joint military drill in five years, lasting for at least ten days.

Pyongyang considers the exercise an invasion rehearsal and says it tested submarine-fired cruise missiles in an apparent protest. Last week, North Korean leader Kim Jong Un ordered his troops to be ready to repel rivals' "frantic war preparation moves."

South Korean President Yoon's office instructed the country's military to proceed with ongoing exercises with the US army, conduct some planned intensive joint drills, and strengthen Seoul-Washington-Tokyo security cooperation.

While expanding military exercises with the US, the Yoon government also hopes for Washington's more substantial promises to use its nuclear weapons to protect South Korea from the North.

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Will the alliance be expanded?

The increasing aggression of both China and North Korea has pushed the US to intervene more in East Asian alliances. Therefore, the US will likely seek to expand the coalition and intensify its regional presence.

The US has expedited its efforts recently, especially after North Korea test-fired more than 70 missiles, many of them nuclear-capable weapons, in 2022. US Ambassador to Japan, Rahm Emanuel, said his country and its two allies, Japan and South Korea, had about 40 trilateral meetings before the Tokyo summit. 

The Biden administration is not the only one who wants more allies. "We must further strengthen cooperation among the allies and like-minded countries," Japanese Prime Minister Fumio Kishida said during the summit.

On the other hand, the South Korean government is decisive in remaining committed to the denuclearisation of the Korean Peninsula, which attaches more importance to trust between the allies, even though none of them has succeeded in ending Pyongyang's nuclear ambitions.

READ MORE: What's on the table for the Kishida-Yoon summit?