The United States will tap its full arsenal of nuclear and conventional defence weapons to defend its allies Japan and South Korea, Secretary of State Rex Tillerson has said after a meeting with his counterparts from both countries.
Washington "remains steadfast in its defence commitments to its allies", he stressed on Thursday on the sidelines of the Group of 20 foreign ministers' meeting in Bonn, Germany.
Mr Tillerson's counterparts are Mr Fumio Kishida from Japan and Mr Yun Byung Se from South Korea. The three also reportedly shared notes on the assassination of Mr Kim Jong Nam, the half-brother of North Korean leader Kim Jong Un, in Malaysia on Monday.
The three-way talks are the first since last September, and follow Pyongyang's latest ballistic missile test that has been widely condemned. That test on Sunday involved a new type of rocket and has been seen as a significant boost for the wayward North's nuclear armoury.
In a joint statement, Mr Tillerson, Mr Kishida and Mr Yun noted "North Korea's flagrant disregard for multiple United Nations Security Council resolutions that expressly prohibit its ballistic missile and nuclear programmes".
They affirmed that they will collaborate to ensure "all countries fully and effectively" implement sanctions under the UN resolutions, adding: "Nations that border North Korea or are affected by the regime's destabilising behaviour all urge North Korea to refrain from provocative actions."
No names were cited but China, which was critical of the launch, is often seen as not doing enough to curb the North's nuclear ambitions despite its economic influence over the country.
The US, Japan and South Korea, which have been sharing military intelligence under a trilateral pact since 2014, agreed to further enhance security cooperation.
Japan and South Korea, both within range of the North's missiles, now host tens of thousands of US troops. The US is also due to deploy its Terminal High Altitude Area Defence anti-missile system in South Korea, though the three ministers did not comment on Thursday when asked if the system would also be sent to Japan to bolster its defences.
Last November, Tokyo and Seoul set aside their historical mistrust to ink a bilateral pact to directly share sensitive information.
However, Japan last month withdrew two diplomats - its ambassador to South Korea and consul- general to Busan - after activists installed a "comfort woman" statue in front of the Japanese consulate in the South Korean city.
The term "comfort women" is a euphemism for girls and women from South Korea, China, the Philippines and elsewhere who were forced to work in Japanese military brothels in the 1930s and 1940s.
Political watcher Jeffrey Kingston of the Temple University in Tokyo told The Straits Times: "Japan and South Korea are not exactly cooperating well because of unresolved historical grievances. The US wants them to get over the past but these 'frenemies' are far from that stage."
In a commentary for The Diplomat magazine yesterday, Mr Ki Suh Jung, an Asia-Pacific fellow at Young Professionals in Foreign Policy, said: "Improved diplomatic relations could act as a jumping- off point for expanded cooperation in the realm of security."
It remains unclear when Japan's two diplomats will return to their posts in South Korea, but Mr Kishida and Mr Yun were due to hold talks in Bonn yesterday over the "comfort women" issue.