Russia freed U.S. journalist Evan Gershkovich and ex-U.S. Marine Paul Whelan on Thursday as part of the biggest prisoner exchange of its kind since the end of the Cold War.

The White House said the U.S. had negotiated the trade with Russia, Germany and three other countries. The deal, negotiated in secrecy for more than a year, involved 24 prisoners, including 16 moving from Russia to the West and eight prisoners held in the West being sent back to Russia.