Russia has released an American teacher imprisoned over what his family said was prescribed medical marijuana, but several other Americans are still detained.

Marc Fogel, an American teacher who was deemed wrongfully detained by Russia, has been released and returned to the U.S. in what the White House described as a diplomatic thaw that could advance negotiations to end the war in Ukraine.

The State Department says an American schoolteacher arrested in Russia on drug charges more than three years ago has been designated by the U.S. government as wrongfully detained.

A court in Russia’s far eastern city of Vladivostok has convicted a visiting American soldier of stealing and making threats of murder, and it sentenced him to three years and nine months in prison.