SEOUL, South Korea (AP) — The national security advisers of the United States, South Korea and Japan called on Saturday for a stronger international push to suppress North Korea’s development of nuclear weapons and missiles and its military cooperation with other countries amid concerns about its alleged arms transfers to Russia.

The meeting in Seoul came as tensions on the Korean Peninsula are at their highest in years, with North Korean leader Kim Jong Un accelerating the expansion of his nuclear and missile program and flaunting an escalatory nuclear doctrine that authorises the preemptive use of nuclear weapons.

The United States and its Asian allies have responded by increasing the visibility of their trilateral security cooperation in the region and strengthening their combined military exercises, which Kim condemns as invasion rehearsals.

US and Japanese officials said Saturday’s three-way talks would include discussions on North Korea’s recent launch of its first military reconnaissance satellite, which Kim has described as crucial for monitoring US and South Korean military activities and enhancing the threat of his nuclear-capable missiles.

Washington, Seoul and Tokyo have also expressed concerns about a potential arms alignment between North Korea and Russia. They worry Kim is providing badly needed munitions to help Russian President Vladimir Putin wage war in Ukraine in exchange for Russian technology assistance to upgrade his nuclear-armed military.

Following the meeting, US national security adviser Jake Sullivan said Washington will strengthen its coordination with Seoul and Tokyo to respond to North Korean cyber crimes and other efforts to bypass US-led international sanctions aimed at choking off funds going to its nuclear weapons and missile program.

Sullivan held separate bilateral talks Friday with South Korea’s national security office director, Cho Tae-yong, and Japan’s national security secretariat secretary general, Takeo Akiba.

Sullivan also met with South Korean President Yoon Suk Yeol.

At a dinner reception for Sullivan and Akiba on Friday, Yoon said it is critical the three countries continue to build on his August summit with US President Joe Biden and Japanese Prime Minister Fumio Kishida at Camp David, where they vowed to deepen security and economic cooperation.

South Korea’s presidential office said Sullivan during his bilateral meeting with Cho on Friday reaffirmed the United States’ strong commitment to defend its ally in the face of North Korean threats.

Sullivan also expressed support for the South’s recent decision to partially suspend a 2018 inter-Korean military agreement on reducing border tensions, which had established border buffers and no-fly zones, to strengthen front-line surveillance of the North, the office said.

At their one-on-one meeting Friday, Cho and Akiba discussed strengthening trilateral cooperation with Washington and building broader “international solidarity” to respond to North Korea’s nuclear and missile program. They said it poses a threat “not only to the Korean Peninsula, but also to the regional and international community as a whole,” Seoul said.

The US, South Korean and Japanese national security advisers last held a trilateral meeting in June in Tokyo.