Russian President Vladimir Putin toasts with North Korean leader Kim Jong Un after their talks in Vladivostok, Russia, Thursday, April 25, 2019. (Alexei Nikolsky, Sputnik, Kremlin Pool Photo via AP)

SEOUL — When North Korean leader Kim Jong Un met Russian President Vladimir Putin in Vladivostok on Thursday, one man was conspicuous by his absence.

Kim Yong Chol — a hard-line veteran, four-star general, former spy chief and one of Kim Jong Un’s closest aides — was nowhere to be seen.

Until now, Kim Yong Chol had been at the forefront of North Korea’s diplomatic outreach and in charge of denuclearization talks with the United States, personally delivering a letter from his leader to President Trump in January, and acting as counterpart to Secretary of State Mike Pompeo.

But South Korea’s National Intelligence Service believes that Kim Yong Chol has been removed from his post as head of the United Front Department, a ruling-party body in charge of ties with South Korea, Yonhap news agency reported, citing a lawmaker.

Kim Yong Chol appears to have been “censured” after the breakdown of the second Trump-Kim summit in Hanoi in February, Lee Hye-hoon, head of the parliamentary intelligence committee, told Reuters.

Experts cautioned that it is still too early to be sure what is happening in North Korea’s notoriously opaque system.

Michael Madden, an expert on North Korea’s leadership at the Stimson Center, said several inaccurate intelligence reports and rumors have surfaced about Kim Yong Chol’s status going back to the fall of 2018, and he noted the latest report has not been corroborated.

Kim Yong Chol also retains an important role at the height of North Korean politics as a member of the State Affairs Commission and of the Political Committee.

But if indeed he has been moved aside as chief negotiator, there would probably not be too many sad faces in Washington.

Kim Yong Chol had a reputation as a fearsomely hard person to deal with, and various media reports have suggested that Pompeo would have preferred to sit across from the more personable and English-speaking foreign minister, Ri Yong Ho.

Kim Yong Chol has reportedly been replaced as head of the UFD by Jang Kum Chol, a relative unknown, which might suggest that the center of gravity for handling U.S. relations might be shifting back to the diplomats at the Foreign Ministry, said Duyeon Kim at the Center for a New American Security. But she cautioned that it is too soon to be sure and that observers need to wait and see who lines up across from Pompeo in any future talks.

“Seeing how upset Kim Jong Un was with the Hanoi results going home empty-handed, I had suspected someone might be replaced or even purged,” she said. “The timing of this reported shake-up seems to fit this hypothesis, but it’s still early, and we’ll know better when negotiations resume.”

When Kim Jong Un sat across from Putin and his team in Vladivostok, he was joined by Foreign Minister Ri and Vice Foreign Minister Choe Son Hui. This was the first time Kim Yong Chol had not accompanied Kim Jong Un on a foreign trip, NK News reported.

If true, the news would also put last week’s North Korean criticism of Pompeo and national security adviser John Bolton in a different context, said John Delury, an associate professor at Yonsei University in Seoul. It would be as though Kim Jong Un was sending Trump a more constructive message, he said: Our negotiators let us down in Hanoi. Let’s replace them and try again.

North Korea’s Foreign Ministry demanded last week that Pompeo be replaced in talks by someone more “mature.” It also accused Bolton of being “dim-sighted.”

“If they actually got rid of Kim Yong Chol, those statements make more sense,” Delury said.

As head of North Korea’s military spy agency, Kim Yong Chol is believed to have been responsible for the sinking of a South Korean naval ship, the Cheonan, in 2010, killing 46 sailors, as well as a 2014 hacking attack against Sony.