U.S. Secretary of State John Kerry met with top officials in Tokyo on Sunday and Monday, reinforcing the U.S. commitment to defend Japan and South Korea against North Korea while stressing at the same time that Washington is willing to negotiate if Pyongyang takes steps toward denuclearization.

Kerry met with Prime Minister Shinzo Abe on Monday for more than an hour. North Korea's belligerent diplomacy was at the top of their agenda, a senior Japanese official said.

The secretary of state, who arrived Sunday after visiting Seoul and Beijing, told Abe that both China and South Korea are committed to trying to get North Korea to end its nuclear weapons program, the official said.