U.S. ambassador to Russia retires amid Ukraine war

U.S. Ambassador to Russia John Sullivan retired and left Moscow on Sunday amid increased tensions between America and Russia following the invasion of Ukraine.

Sullivan, who served as the ambassador since December 2019, will retire after spending four decades in public service. Deputy Chief of Mission Elizabeth Rood will assume Sullivan's duty until a successor arrives, the U.S. Embassy in Russia stated.

The United States and Russia have had a particularly tense relationship following Moscow's invasion of Ukraine in February. 

Russia's Ministry of Foreign Affairs in March told Sullivan that relations between the two countries were on "the verge of breaking" after U.S. President Joe Biden called Russian President Vladimir Putin a "war criminal."