Brittney Griner, the American W.N.B.A. star who has been detained in Russia since February, recently sent a letter to President Biden. “I’m terrified I might be here forever,” she wrote. The White House vowed to use “every tool” to bring Ms. Griner back to the United States, but organizing her release is a tricky proposition, complicated not least by Washington’s break with Moscow over the war in Ukraine. Guest: Michael Crowley, a diplomatic correspondent for The New York Times.