With US foreign policy in flux, Japan and South Korea are finding common ground on trade, defense, and demographic challenges.

On his first official visit to Japan since taking office in June, Lee met Ishiba at the premier's residence in Tokyo to discuss bilateral ties between the East Asia neighbours, including closer security coordination with the United States under a trilateral pact signed by their predecessors.

Since returning to the White House, President Donald Trump has boasted of ending either six or seven wars -- a matter of much dispute -- and has been pushing with mixed success to bring peace to Ukraine.