Hayes has been one of the left's most vehement critics of President Barack Obama's plan of limited airstrikes because of concerns about the legitimacy of the strikes and that it could lead to a larger-scale intervention.
Hayes opened the interview by showing Kerry a video clip from 2012 that was brought to light by a recent New York Times story. It showed certain rebels brutally executing Syrian soldiers.
"If the U.S. attacks
"No," Kerry replied. "In fact, I believe that those men in those videos are disadvantaged by an American response to the chemical weapons use because it, in fact, empowers the moderate opposition.
"We all know there are about 11 really bad opposition groups - so-called opposition. They're not - they're fighting Assad. They are not part of the opposition that is being supported by our friends and ourselves. That is a moderate opposition. They condemn what has happened today and they will - they are and we are busy separating the support we're getting from any possibility of that support going to these guys."
Kerry reiterated that Obama did not intend to engage the U.S. in Syria's civil war. He said that the limited strikes are about responding to Syrian President Bashar al-Assad's use of chemical weapons on his own people, which the U.S. says killed 1,429 people, including 426 children.
"I do not believe this is taking America to war," Kerry said.
After the strikes, he said that the U.S. would continue its support of the "moderate opposition" groups.
Kerry was also asked to respond to criticism by some of the voices in the George W. Bush administration who helped orchestrate the war in Iraq. He didn't have much patience for that criticism.
"It just doesn't make a difference to me, because they're so discredited by their own judgments, that it's hard to see that they have a judgment today that is relevant to this," Kerry said.
"I'll listen to people whose judgment I clearly trust and respect."
Here's the clip:
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