Armed Services Committee Chair Thornberry: 'No Doubt' ISIS Would Use Nukes If Obtained

— -- ISIS would "of course" use a nuclear weapon if given the chance, House Armed Services Committee Chair Rep. Mac Thornberry said today, responding to reports of ISIS claiming they had the resources to acquire a nuclear weapon from Pakistan within a year.

Despite the reports that ISIS hopes to obtain a nuclear weapon, Thornberry, R-Texas, told ABC News' Jonathan Karl on "This Week" that the jihadist group has not taken steps yet, saying that there is "no evidence that it has happened."

"Would they do it if they had the opportunity? Of course. Would they use it if they had it? I don't think there's any doubt," Thornberry said.

"We don't wait until they get it before we take action that seriously degrades and destroys ISIS," Thornberry added. "Secondly, we keep pushing at their finances to lower the amount of money they have."

While the White House is arguing that the U.S. is not losing the war against ISIS even as they gained strongholds in the cities of Ramadi in Iraq and Palmyra in Syria, Thornberry said that ISIS "has a lot of momentum on their side."

"The president resists saying, 'We're losing it.' Well, we're not winning. We know that," Thornberry said.

"You see not only ISIS gaining territory in Iraq and in Syria and I think the map, like you showed, gives it very graphically about their territory expanding," he added.

While Thornberry said he would prefer not having U.S. ground troops fight alongside the Iraqi military, he called for greater intelligence capability and on-the-ground advisers to help combat ISIS.

"Some of our military folks believe, however, if we'd had some advisers on the ground we could have called in effective airstrikes, that it would have at least made the battle for Ramadi more competitive," Thornberry said.

"But the other thing we've got to do is improve our intelligence capability," he said.

Thornberry voted earlier this month for the USA Freedom Act, which would have reformed the government's bulk data collection process. The measure was blocked in a late-night vote in the Senate this weekend, leaving the Patriot Act set to expire on June 1.

"We passed what I think is an imperfect bill out of the House, but it's better than letting it expire," he said. "So we need to have that crucial intelligence capability continue."