Russia called outgoing U.S. Ambassador to Russia Jon Huntsman a professional diplomat late on Tuesday, but said he had been unable to improve battered Russia-U.S. ties because he had been hamstrung by domestic U.S. politics, the state-run TASS news agency reported.

Huntsman, who was appointed by U.S. President Donald Trump in 2017, said in a resignation letter circulated by U.S. media that he was stepping down after a two-year tenure overshadowed by U.S. sanctions on Moscow and tit-for-tat diplomatic expulsions.

His stint in Russia came at a time when relations between Washington and Moscow hit a post-Cold War low and were strained over everything from Syria to arms control and allegations, denied by Russia, that Moscow meddled in the 2016 U.S. presidential election to help Trump win.

"Huntsman is a professional," TASS cited the Foreign Ministry as saying.