A Russian court on Thursday found the American basketball star Brittney Griner guilty of an attempt to smuggle illegal narcotics into Russia and sentenced her to nine years in a penal colony, according to her lawyers. The verdict ended a closely watched trial that her supporters say made her a pawn in a tense geopolitical showdown over the war in Ukraine.

The verdict, virtually preordained in a legal system in which defendants are rarely acquitted, leaves Ms. Griner’s fate subject to diplomatic bargaining between Russia and the United States. The countries have been discussing the possibility of a prisoner exchange that would bring Ms. Griner home from Russia, where she has been detained since traveling there in mid-February.

Officials in Moscow have said that a verdict in her trial was a necessary precondition for a possible exchange for Ms. Griner, an Olympian who is one of the biggest stars of her generation. The United States has said she was wrongly detained, held by Russia as a bargaining chip amid the acrimony with the West over Russia’s war in Ukraine.