Top South Korean, U.S. and Japanese military officers are urging North Korea to cease all unlawful activities that threaten regional security, as the three nations fly advanced warplanes for a joint exercise in a show of force against the North.

South Korea, Japan and the United States conducted a joint air drill on Friday involving a U.S. B-52 strategic bomber and fighter jets of the three allies over international waters, the South's defence ministry said.

Visits are banned by Russia, which occupies Kunashiri, Etorofu, Shikotan, and the Habomai islets, off Hokkaido

Japan’s Emperor Naruhito has met Mongolia's President Ukhnaa Khurelsukh during a visit aimed at strengthening ties between the two democracies.

Rubio and Foreign Minister Sergey Lavrov held talks in Kuala Lumpur on the sidelines of the annual Association of Southeast Asian Nations Regional Forum, which brings together 10 ASEAN members and their most important diplomatic partners including Russia, China, Japan, South Korea, European nations and the U.S.

The top military officials of South Korea, Japanese and the United States urged North Korea on Friday to halt all unlawful activities threatening regional security as the three nations flew advanced warplanes for a joint exercise in a show of force against Pyongyang.

US President Donald Trump has said he will have "a major statement" on Russia on Monday, without going into detail.