Joe Biden had a single-word message for Vladimir Putin after the largest prisoner swap of its kind since the Cold War took place on Thursday.

An MSNBC clip shows reporters asking Biden at Joint Base Andrews: “What is your message tonight to Vladimir Putin?” Biden responds simply: “Stop.”

The U.S. and some of its allies agreed to exchange eight Russian detainees in return for the Wall Street Journal reporter Evan Gershkovich, the former US Marine Paul Whelan and the Russian-American journalist Alsu Kurmasheva, along with a number of Russian dissidents held in Russian prisons.

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