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It is too early to say that the U.S. is succeeding it its campaign against the Islamic State in Iraq and Syria (ISIS), Secretary of Defense Ashton Carter said in an interview broadcast Tuesday morning.

“I think it’s too early to say that we’re winning, but I think we have certainly inflicted a lot of damage,” he said on NBC’s “Today” show

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“But it will take some time to inflict defeat upon ISIL,” he said, using the administration’s preferred acronym for the group. “We’re still building the coalition and building the forces, and that’s why I’m hesitant to say we’re winning. I’m confident we will win.”

He declined to give a timeline for when the fight against ISIS might end.

Last week, the U.S. began a bombing campaign in Tikrit — a city where Iraqi forces are fighting ISIS for control. In part, the operation is designed to show the Iraqi government that they should make the U.S. and its coalition their primary military partners, rather than working with militias backed by Iran, which have been doing the bulk of the fighting in Tikrit.

Carter also addressed other hotspots during the interview.

He brushed off concerns that the disintegration of the government in Yemen, where the capital has been besieged by rebels, would hinder U.S. counterterrorism operations there.

He said American forces would simply have to approach their operations against al Qaeda in the Arabian Peninsula (AQAP), one of the region's most pernicious terrorist groups, “in a different way.”

“We are going to continue to prosecute our counterterrorism operations against AQAP whatever happens on the ground there,” he said.

He was more reticent on other issues, saying he didn’t want to comment extensively on the prisoner swap for Army Sgt. Bowe Bergdahl because an investigation into Bergdahl's conduct was ongoing.

But he did comment on one of the first stories to appear during his tenure as secretary of Defense. Asked about how he took it, when, at his swearing-in ceremony, Vice President Biden put his hands on Carter's wife's shoulders and appeared to whisper in her ear, Carter took it in stride.

“I laughed,” he said of his reaction. “They know each other extremely well. We’re great friends of the Bidens.”