Controversial Russian Ambassador to the U.S. Sergey Kislyak has officially departed the United States as his assignment has come to an end, CBS News' Margaret Brennan reports.

Kislyak became a central player in the ongoing investigation into Russian meddling of the 2016 election. The long-time Washington fixture was involved in a variety of private meetings and discussions with Trump associates, including undisclosed interactions with Mr. Trump's son-in-law Jared Kushner, Attorney General Jeff Sessions, former national security adviser Michael Flynn and former Trump campaign adviser Carter Page.

Sessions recused himself from the Russia investigation after revelations he had met with Kislyak during the campaign. Flynn was forced out as national security adviser for misleading Vice President Mike Pence about phone calls he had with Kislyak during the transition in which they discussed lifting sanctions against Russia.

According to the Russian embassy, Kislyak has left the U.S. as part of a long-scheduled reassignment. The new ambassador has reportedly not yet arrived to the U.S.

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An embassy spokesman said the current deputy chief of mission will be acting ambassador pending the arrival of Kislyak's successor.

Kislyak became Russia's ambassador to the U.S. in 2008 after working as an ambassador to NATO from 1998 to 2003. He was deputy foreign minister from 2003 to 2008.