Story highlights

President Obama lays out a worst-case scenario in which ISIS gains a nuclear weapon

In such a case, the President says he'd use U.S. ground troops against ISIS

Democrat Dick Durbin, Republican Mitt Romney both take exception

CNN  — 

The question of whether there should be American boots on the ground to fight ISIS in Iraq came up again Sunday after President Barack Obama said that despite his earlier vow not to commit U.S. combat forces there, he wasn’t ruling out the possibility if confronted with the worst-possible situation.

“There are always circumstances in which the United States might need to deploy ground troops,” Obama said at the G20 Summit in Australia.

“If we discovered that ISIL had gotten possession of a nuclear weapon, and we had to run an operation to get it out of their hands, then yes, you can anticipate that not only would [Joint Chiefs Chairman Gen. Martin] Dempsey recommend me sending U.S. ground troops to get that weapon out of their hands, but I would order it.”

The comments – along with the release Sunday of an ISIS video depicting the aftermath of the beheading of American hostage Peter Kassig – reignited the debate on the Sunday morning talk shows.

“I will tell you many of us feel, I think the American people feel, it would be a serious mistake for us to make a commitment of land troops into these theaters,” Sen. Dick Durbin, D-Illinois, told Candy Crowley on CNN’s “State of the Union.”

Former GOP presidential candidate Mitt Romney, however, thought Obama was wrong in ruling out sending U.S. ground troops, saying on CBS’ “Face the Nation,” “You don’t tell the enemy exactly what you plan on doing or what you won’t do.”

“As a result of the mistakes that have been made in the past on the President’s part, we now have terrible visions being shown on TV and of course a threat to ourselves here in the homeland,” Romney said. “And the right course for this nation is to do whatever it takes to destroy and defeat ISIS.”

Dempsey has suggested at least twice that he would recommend U.S. ground troops if he felt they were needed, although he has emphasized he has not yet decided it’s necessary to do so.

Durbin, when asked whether he would support troops if the current strategy is not enough, replied, “I can tell you there are many who are anxious to send troops forward, I am not one of them.”