Two prominent Americans held by Russia—Wall Street Journal reporter Evan Gershkovich and former Marine Paul Whelan—returned to the U.S. last week as part of a massive, multi-country prisoner swap.

That swap included the freeing of 16 prisoners including citizens of Germany as well as Russian political prisoners. In exchange, eight Russian prisoners in the U.S., Germany, Poland, Norway, and Slovenia were released. The swap marks the largest prisoner exchange with Russia since the Cold War.

Experts note that it’s important to differentiate between the individuals released by Russia and those released by other countries.

“Putin wanted to bring home a Russian assassin, one he allegedly knew personally, and other spies, to show people who work in the Russian intelligence services that their government will try to bring them home if they get caught. The U.S. government and its allies wanted to free innocent people being held hostage in Russian prisons,” says Brian Taylor, professor of political science and director of the Moynihan Institute of Global Affairs.

Read more in the Vox article, “The US-Russia prisoner swap that freed Evan Gershkovich, explained.”