Biegun initially received a cold shoulder from North Korean officials who, mindful that the countries’ leaders were negotiating directly about Pyongyang’s nuclear programme, saw little reason to deal with an envoy on anything other than logistics of meetings.

But Biegun enjoyed a breakthrough of sorts in early October when he met North Korea’s lead negotiator Kim Myong-gil in Sweden.

North Korea walked away from the talks, denouncing the US attitude, but the United States issued a comparatively upbeat statement saying that Biegun never planned to resolve all issues in a day and that the two sides would meet again.

At a time of deep polarisation in Washington, Biegun, 56, has won respect across party lines and in foreign capitals for his affability and for offering cogent analysis rather than ideological lectures.

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A lifelong Republican, Biegun spent his career in behind-the-scenes roles in Congress and in former president George W. Bush’s administration, where he served in senior staff positions at the White House and State Department.

Unlike Sullivan, who is expected to be confirmed to go to Moscow, Biegun’s expertise in fact lies in Russia, where he lived from 1992 to 1994 as part of US democracy promotion work.

In an interview with an alumni publication at the University of Michigan, Biegun recalled that he became fascinated by Russia when a high school history teacher wrote “tsar” in Cyrillic script.

“It was one of the most exotic things I’d ever seen. It left such an impression on me that I went to the town library and checked out a book to teach myself Russian,” he said.

A native of Michigan, Biegun is the third generation of his family to work at the Ford Motor, handling the carmaker’s relations with foreign governments before being tapped as the North Korea envoy.