John Sullivan, who served as U.S. ambassador to Russia as President Vladimir Putin invaded Ukraine and returned full-scale war to the European continent, has left his post and departed Moscow, the U.S. Embassy in Moscow said in a statement Sunday.

“Following his departure, he will retire from a career in public service that has spanned four decades and five U.S. presidents, including service as the Deputy Secretary of State and in senior positions at the Departments of Justice, Defense, and Commerce,” the statement said.