U.S. Under Secretary of State Thomas Shannon (C) speaks to media after a meeting with Japan's National Security Council head Shotaro Yachi (not in picture) at Prime Minister Shinzo Abe's official residence in Tokyo, Japan June 13, 2017. REUTERS/Issei Kato

TOKYO (Reuters) - U.S. Undersecretary of State Thomas Shannon said on Tuesday that North Korea’s nuclear and intercontinental ballistic missile (ICBM) program would make the reclusive state a global threat if it became successful over time.

Shannon made the comment to reporters in Tokyo after his meeting with Japanese Prime Minister Shinzo Abe’s top national security adviser, Shotaro Yachi.

Under third-generation leader Kim Jong Un, North Korea has been conducting missile tests at an unprecedented pace in an effort to develop an intercontinental ballistic missile capable of striking the mainland United States.