Foreign Minister Taro Kono made the request in separate talks in Washington earlier this month with US Defense Secretary James Mattis, Mike Pompeo, director of the Central Intelligence Agency and Trump’s nominee for next secretary of state, and Deputy Secretary of State John Sullivan, the sources said.

Kono also asked the US officials to ensure that before Trump meets Kim in May for an unprecedented US-North Korea summit, Pyongyang will promise to promote a complete, verifiable and irreversible denuclearization, accept International Atomic Energy Agency inspections and abolish chemical weapons, they said.

Prime Minister Shinzo Abe is expected to make a similar request concerning preconditions when he visits the United States in mid-April for talks with Trump.