On Saturday, five American prisoners were released from Iran—including Washington Post reporter Jason Rezaian and Matthew Trevithick, a Hingham man who was imprisoned while studying language in Tehran.

The peaceful release was a victory for diplomacy and for President Obama's nuclear deal with Iran reached this past July, said Charles Sennott, head of The GroundTruth Project. Sennott joined "Boston Public Radio" with Jim Braude and Margery Eagan live on the line from Jordan, where he is advising a team of reporters and fellows covering the refugee crisis.

"It was terrible these people were held for so long. It speaks volumes of the tyranny of this Iranian regime. But it also speaks loudly about the possibility of diplomacy, that now they're out," Sennott said.

The nuclear deal came under scrutiny recently when 10 American sailors were held captive by Iran after their ship was found in Iranian waters. Iran released a video of the captured soldiers on their knees being held at gunpoint, a spectacle that made Secretary of John Kerry—who led the Obama Administration's negotiations of the deal— "very angry," he told CNN today. The prisoners were later released.

If anything, Sennott said, the nature of the spectacle demonstrated just why such a deal was necessary in the first place—to prevent a regime as dangerous as Iran from acquiring nuclear weapons, and to open diplomatic channels so incidents like this one could be quickly and peacefully resolved in the future.

"The spectacle revealed who Iran is. There's no question, this is a regime that has blood on its hands, that has been involved with state-sponsored terrorism," Sennott said. "The intention of the Iran deal isn't to say Washington now has no problem with Iran; it's to say: we need to stop a country, with this terrible a track record, from having a nuclear weapon." 

"In the aggregate, look: diplomacy works," he said. "Diplomacy is a good strategy. Diplomacy can change the world,"

Charles Sennott is a journalist and head of The GroundTruth Project. To hear more from his interview, tune into Boston Public Radio above.