The official, Kim Yong Chol, was greeted by White House chief of staff John Kelly, who led him to the Oval Office for talks with Trump and Secretary of State Mike Pompeo, according to press secretary Sarah Sanders.

Kim Yong Chol arrived in Washington from New York, where he met with Pompeo on preparations for the planned June 12 encounter between the US and North Korean leaders in Singapore.

After Thursday's talks, Pompeo expressed confidence that the process was moving in the right direction, but warned that the North's young leader must be bold enough to make a "strategic shift" in understanding that he will be safer without nuclear weapons.

US officials said the letter from Kim to Trump may not clear up all the questions about the agenda, but may bring the planned Singapore meeting a step closer.