U.S. Defense Secretary Mark Esper has reportedly said North Korea remains a significant source of concern. 

According to Japanese media, including the Yomiuri Shimbun and Kyodo News, Esper made the remark in his meeting with Japanese Prime Minister Shinzo Abe in Tokyo on Wednesday, following a series of missile launches from the North. 

Esper reaffirmed Washington’s position that it will cooperate with Japan to realize a joint goal of complete denuclearization of North Korea. 

Later in the day, he also met with Japanese defense minister Takeshi Iwaya. Kyodo reported that they two officials shared the perception that it is important for the U.S. and Japan to continue cooperation with South Korea in dealing with the North, including a military information sharing pact between Seoul and Tokyo.