ANTALYA, Turkey (AP) -- President Barack Obama on Monday 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 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.