ANTALYA, Turkey » President Barack Obama firmly rejected calls for a shift in U.S. strategy against the Islamic State following the Paris attacks, saying Republicans who want to send ground troops into the volatile region are “talking as if they’re tough” but fail to understand the potentially grave consequences.

“Folks want to pop off and have opinions about what they think they would do,” Obama said today in a news conference wrapping up a two-day summit of world leaders in Turkey. “If they think that somehow their advisers are better than the chairman of my Joint Chiefs of Staff and the folks who are actually on the ground, I want to meet them. And we can have that debate.”

In a stinging rebuke, the president condemned Republicans who have suggested U.S. assistance to refugees fleeing the Middle East should focus on Christians, not Muslims. GOP presidential candidates Jeb Bush and Ted Cruz have made such suggestions, while some Republican governors want to ban all Syrian refugees from their states.

“That’s shameful,” he said. “That’s not American. It’s not who we are.”

Republican National Committee Chairman Reince Priebus called Obama’s statements “excuse-laden and defensive.”

Even before the Paris attacks, Obama was under pressure from allies and his own administration to show progress in the campaign against the Islamic State. The assault in the heart of Western Europe was part of a troubling pattern showing the group focusing new attention on targets outside its base in Iraq and Syria.

Obama conceded that the attacks in France marked a “terrible and sickening setback” in the anti-Islamic State campaign. But he insisted his strategy of building an international coalition to launch airstrikes, while training and equipping more moderate forces on the ground, is the best approach.

“The strategy that we are putting forward is the strategy that ultimately is going to work,” Obama said. “It’s going to take time.”

The president has deployed more than 3,000 U.S. troops to Iraq to assist local security forces, and he recently announced plans to send 50 special operations forces to Syria. But he’s vowed to avoid the kind of large-scale ground combat that U.S. troops engaged in for years in Iraq and Afghanistan.

Obama appeared emotional as he spoke of the consequences of war, referencing the injured troops he visits at Walter Reed, a military hospital near the White House.

“Some of those are people I’ve ordered into battle,” he said.

He said the U.S. would have to be prepared for a permanent occupation in Syria or Iraq if he sent in ground forces.

“What happens when there’s a terrorist attack generated from Yemen?” Obama asked. “Do we then send more troops into there? Or Libya, perhaps? Or if there’s a terrorist network that’s operating anywhere else — in North Africa, or in Southeast Asia?”

The potency of the Islamic State, along with the civil war in Syria that gave the group space to rise, dominated Obama’s two days of talks in Turkey, where leaders from the Group of 20 rich and developing nations gathered at a seaside resort. From Turkey, Obama headed to Asia for regional summits in the Philippines and Malaysia.

The president said he was eager to see other nations step up the fight against the Islamic State. While the White House frequently heralds the more than 60 countries that are part of the coalition fighting the extremists, the U.S. has carried out the bulk of the airstrikes.

France has ramped up its involvement following the attacks on Friday that killed at least 129 people and injured hundreds. In its heaviest strikes yet, the French military bombarded Raqqa, the Islamic State’s stronghold in Syria, in hopes of killing Islamic State organizers and trainees.

Obama announced a new effort to share intelligence with France following the attacks, including helping the French military identify targets for the airstrikes.

The Islamic State’s increasing focus on wider targets has raised questions about whether Obama underestimated the group. He once referred to the extremists as a “JV team” and said shortly before the Paris attack that their capacity in Iraq and Syria had been contained.

Obama dismissed the suggestion that he failed to comprehend the Islamic State’s strength, but said there were challenges in defeating a group whose fighters have a “willingness to die.”

“If you have a handful of people who don’t mind dying, they can kill a lot of people,” he said.

While officials say the U.S. had been aware of the Islamic State’s desire to strike targets outside the Middle East, Obama said he had not been briefed on any intelligence that indicated an attack in Paris was likely.

“I’m not aware of anything that was specific,” he said.