North Korean leader Kim Jong Un’s right-hand man and one of the top officials involved in nuclear talks with the United States, Kim Yong Chol, has been replaced as chief of a key espionage agency handling inter-Korean affairs, a report said Wednesday.

Kim Yong Chol, head of the United Front Department, was recently replaced by Jang Kum Chol, South Korea’s Yonhap news agency reported, citing an official with the country’s parliamentary intelligence committee.

The official did not state a reason for the dismissal. The Japan Times could not immediately confirm the report, but Kim Yong Chol was notably absent from Kim Jong Un’s entourage that arrived in the Russian Far East city of Vladivostok on Wednesday for a summit with President Vladimir Putin, according to images and video of the leader’s departure and arrival.

It was the first time that Kim Yong Chol had not accompanied the North Korean leader on a trip abroad.

The hard-liner and former spy chief was heavily involved in the North Korean leader’s February summit with U.S. President Donald Trump in Hanoi that ended in no deal, in part over the North’s demands for immediate sanctions relief.

The news came just days after the North lambasted Kim Yong Chol’s counterpart in the U.S. nuclear negotiations, Secretary of State Mike Pompeo, calling for his ouster and demanding a “more careful and mature” negotiator.

According to the North Korean leadership watch website, Jang Kum Chol was appointed as a department director with the ruling Workers’ Party of Korea’s Central Committee during a plenary session of the central committee held in central Pyongyang on April 10. An archived dispatch from the state-run Korean Central News Agency detailing a 2014 seminar said a person by that name had served as chairman of the country’s Academy of Social Sciences Committee, which has played a key role in the North’s nuclear program.