Here's why Obama won't send troops into Syria to destroy ISIS

Even though one of the Paris attackers may have entered Europe as a Syrian asylum seeker, President Barack Obama isn't having second thoughts about bringing up to 10,000 Syrian refugees to the USA, one of his top aides said Sunday. "That's why, frankly, we've been waging war against ISIL now for over a year".

SC Sen. Lindsey Graham, a long-shot Republican candidate, said a successful strategy to defeat the Islamic State must include a certain number of ground troops.

Obama used much of the press conference to strike back at his critics, sounding at times defensive and combative.

Obama made his remarks after the the deadly attacks in Paris carried out on Friday by the so-called Islamic State left at least 129 dead and hundreds more injured. The USA has been conducting air strikes and has advisers with Iraqi and Kurdish units, but Obama has refused to send in combat troops. "A few of them seem to think that if I were just more bellicose in expressing what we are doing that that would make a difference, because that seems to be the only thing that they're doing, is talking as if they're tough", he said.

"The values that we're fighting against ISIL for", he said, "are precisely that we don't discriminate against people due to their faith".

He continued, "if folks want to pop off and have opinions about what they think they would do, present a specific plan. But I think we do need to do our part to take those refugees who are in need". France has been more aggressive than the United States in pushing for punitive measures against Assad's government: It led the call for airstrikes against his regime following his alleged use of chemical weapons in 2013 and has been aiding anti-Assad rebel groups since 2012.

The fruits of that cooperation were borne Sunday night, when French jets began a bombardment of Raqqa, the Syrian headquarters of ISIS.

No war in history has ever been won by air power alone. He rejected a safe "no-fly" zone as well intentioned but unworkable.

Obama was speaking just before departing from the G20 summit, being held at a Turkish resort 500 miles from the Syrian border. The summit had been scheduled before the terror attacks in Paris last week and went ahead as scheduled.

The president is also looking to Russian President Vladimir Putin and Saudi Arabian King Salman to help broker a ceasefire in Syria. "And without our leadership in building a coalition to destroy ISIS, it won't happen".

But there appeared to be little appetite among foreign leaders here for a large-scale ground effort in Syria.

They've also brought new scrutiny to the flood of refugees from Syria, which Obama has said must prompt new measures by European nations to accommodate those fleeing their country's civil war. French officials yesterday were still trying to identify people involved in the Paris conspiracy, and said as many as three of the seven suicide bombers who died in the attacks were French citizens.

Obama's comments came as French President François Hollande said the attacks on Paris were "planned in Syria, organized in Belgium and perpetrated on our soil with French complicity".

"Today again I'm calling on leaders to commit the resources that this fight demands", Obama added. "That's not who we are. We don't have religious tests (for) our compassion". Ted Cruz and former Florida Gov. Jeb Bush have advocated for limiting the flow of refugees, while including a special exemption for Christians.

Ben Rhodes, Obama's deputy national security adviser, said yesterday the US has a "very careful vetting process" for all Syrian refugees and will not be changing course.

"The overwhelming majority of victims of terrorism ... are Muslims", Obama added later.