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.

At a summit meeting in Washington, D.C. on Monday, the U.S. and South Korean presidents will discuss modernizing their 71-year-old alliance and fleshing out a trade deal reached last month.

President Lee Jae Myung's visit is expected to spotlight trade, alliance costs and North Korea as he seeks to set the tone with Trump's second-term White House.