The United States will not support all of the rebels in the Syrian civil war, and the U.S. will not become directly involved in the war, said U.S. Secretary of State John Kerry during an exclusive interview with MSNBC’s Chris Hayes Thursday. Kerry said that the intervention proposed by the White House would prop up the moderate opposition and harm Basher al-Assad.

“This action has nothing to do with engaging directly in Syria’s civil war on one side or the other,” said Kerry. However, he also said that the U.S. wants Assad to step down and argued that an American response would “have a downstream impact on Assad’s military capacity.”

Kerry made the case before Congress this week for taking punitive action against Assad’s regime for its alleged use of chemical weapons against civilians last month. President Obama is making a similar argument for intervention at the St. Petersburg G-20 summit, where he hopes to build international support.

The proposed military strike against Syria, said Kerry, is only about “enforcing a norm of international behavior,” and making clear that dictators cannot use chemical weapons with impunity.

“What the president is trying to do, and what we believe is important to America’s national security interests, and to humanitarian interests, and to the interests of Israel, and Jordan, and Lebanon, and all of our friends in the region, is that you hold Bashar al-Assad responsible for use of chemical weapons, and that you degrade his ability to use them again, and deter him from using them again,” he said. “That’s what’s really important here. And that’s all that we’re talking about in this.”

Though the strike might weaken Assad, it would not make the United States into a de facto ally of his most radical opponents, said Kerry. He predicted that extremists, such as the ones who were recently captured on video executing seven prisoners, would be weakened by the same intervention aimed at their primary foe.

“I believe that those men in those videos are disadvantaged by an American response to the chemical weapons used because it in fact empowers the moderate opposition,” he said. “We all know there are about 11 really bad opposition groups—so-called opposition. They are 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 we are busy separating the support we are giving from any possibility of that support going to these guys.”

As for whether the United States would be forced to act again if Assad continued to use chemical weapons, Kerry said he was “convinced” that the proposed intervention “will not lead to some further engagement.” The administration believes that Assad will not strike again if he faces the consequences the first time around, and it has been made “crystal clear” to the opposition that they should not expect further intervention on their behalf.

“There will be no American boots on the ground,” he said. “This is not Iraq, this is not Afghanistan, this is not even Libya. This is a very limited, targeted effort.”

Asked to comment on the criticism being directed at the administration by some of the Bush-era architects of the Iraq War, Kerry brushed it aside.

“It just doesn’t make a difference to me because they’re so discredited by their own judgments,” he said.

Watch part 1 of Chris Hayes’ full interview with Kerry in the video player above. Watch part 2 in the player below.