TEHRAN — (CNN) When Iranian officials released footage of 10 U.S. sailors being taken captive, it made John Kerry “very, very frustrated,” the secretary of state told CNN on Monday.

Kerry has been negotiating with Iran on a number of fronts for well over a year, including on the President’s nuclear deal and a prisoner swap completed over the weekend.

But after U.S. Navy vessels “regrettably, inadvertently” drifted into Iranian waters, per Kerry, and the 10 sailors were taken by Iranians on Tuesday, Iran’s military released footage of the troops with their hands behind their heads at gunpoint.

Though the sailors were released within 24 hours, the footage was inflammatory.

“I was very angry. I was very, very frustrated and angry that that was released,” Kerry told John Berman on CNN’s “New Day.” “I raised it immediately with the Iranians. It was not put out by the Ministry of Foreign Affairs or the government directly, it was put out I think by the military over there, the (Revolutionary Guard), who is opposed to what we are doing.”

Kerry said, though, that because of the negotiations that have been ongoing, he was able to rapidly secure the sailors.

“The challenge is three or four years ago, we wouldn’t have known who to call … and it could have grown into a major kind of hostage confrontation the way it had previously,” Kerry said. The progress “could not have happened were we not building on this path with respect to the nuclear program,” he added.

He would not divulge what he said to his counterparts about the sailors but stressed that he was firm.

“I’m not going to discuss what I said or didn’t say, but suffice it to say I made it crystal clear how serious this was, it was imperative to get it solved … and within hours we had an agreement,” Kerry said.

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