What the 2016 Presidential Candidates Say the US Should Do About ISIS

— -- It became the leading topic of discussion during Saturday’s Democratic presidential debate: What should the United States do in the fight against ISIS following the attack on Paris?

In the days since the massacre overseas, the presidential hopefuls have offered an array of opinions, with several of the Republicans contenders coming out in favor of doing more; even if that means American "boots on the ground."

One of the Paris attackers reportedly crossed into Europe alongside Syrian refugees, providing fuel to the argument, made by some GOP candidates, that ISIS could infiltrate the 10,000 Syrian refugees President Obama vowed to accept over the next year.

Today, former Florida Gov. Jeb Bush told Fox News that the United States should “absolutely” be profiling in order to prevent Islamic terrorists from crossing our borders and Republican Sen. Ted Cruz Sunday said the United States should accept Christian refugees but not Muslims.

Here's a look at what the 2016 candidates have been saying about how they would handle the threat posed by ISIS:

HILLARY CLINTON

Hillary Clinton argued during the debate that military forces should be used as a last resort, but that ISIS “cannot be contained. It must be defeated.”

“There is no question in my mind that if we summon our resources, both our leadership resources and all of the tools at our disposal, not just military force, which should be used as a last resort, but our diplomacy, our development aid, law enforcement, sharing of intelligence in a much more open and cooperative way, that we can bring people together,” Clinton said.

“But it cannot be an American fight. And I think what the president has consistently said, which I agree with, is that we will support those who take the fight to ISIS.”

While Clinton was criticized by her challengers Saturday night for saying combating ISIS "cannot be an American fight,” she said Sunday at a barbecue in Ames, Iowa, that “America has to lead.”

BERNIE SANDERS and MARTIN O’MALLEY

That’s where Bernie Sanders and Martin O’Malley were quick to jump on Clinton’s assessment that the fight against ISIS cannot be an American fight. Sanders said Saturday during the debate that the bulk of the responsibility is America’s and that we need to “lead an international coalition which includes very significantly the Muslim nations in that region who are going to have to fight and defend their way of life.”

Martin O’Malley stated: “This actually is America's fight. It cannot solely be America's fight. America is best when we work in collaboration with our allies.”

O’Malley said on CNN’s New Day that we should deploy more special operations advisers, but if “there is to be greater American involvement, it's not going to be a matter of sending in the third Marine division.”

DONALD TRUMP

Appearing on MSNBC’s “Morning Joe,” Trump said today he would consider sending 10,000 U.S. troops and engage other countries in the region to fight ISIS.

He also indicates, as he has before, that he was open to the idea of shutting down certain mosques in the United States.

"I would hate to do it, but it's something that you're going to have to strongly consider," Trump added.

JEB BUSH

Bush argued today in an interview on CBS’s “This Morning” that President Obama does not have a strategy. Bush’s “strategy necessary to defeat ISIS” would include more boots on the ground.

“And I think it would be require more boots on the ground, if you will, or more troops on the ground, more special operators, more people that are embedded in the Iraqi army, for example, more training for the Peshmerga forces and more engagement with the Sunni tribal leaders,” Bush said today.

He did not speculate on specific numbers of U.S. troops he would send into Syria.

Bush also believes that there is a “special” need “to make sure that Christians from Syria are being protected.”

“We should focus our efforts as it relates to refugees on the Christians that are being slaughtered,” Bush said on CNN Sunday.

BEN CARSON

Carson is proposing a multinational coalition in the region, including U.S. troops to accomplish the complete elimination of ISIS.

"Boots on the ground would probably be important, because throughout that whole Middle East region, we have been calling for a coalition of people who have a vested interest," Carson said. "We have not seen a coalition form, but that's because there has been no leadership."

When he was asked Sunday by Fox’s Chris Wallace three times who he would name to a coalition to fight ISIS, Carson had trouble naming someone and ultimately said president has an array of resources available besides the Pentagon.

“We need to use our intelligence to a much greater extent, our intelligence agencies. I think looking at the ideological war being waged by the jihadists has been very effective. We need to wage a counter-war against them utilizing social media, and the mechanisms they use. And the clerics, we need to be putting pressure on them to disavow what ISIS is doing,” Carson said.

MARCO RUBIO

Asked by ABC News’ George Stephanopoulos on “This Week” how he would respond to the Paris terror attacks as president, Rubio replied he would invoke NATO’s Article 5, which declares an attack on one ally to be an attack on them all.

Rubio also called for more airstrikes and special operations, but argued it was “premature" to talk about the exact number of boots on the ground.

Rubio added: "We also need to get our Sunni allies more involved in this fight. The only way to defeat ISIS ideologically and militarily is by Sunni themselves.”

Another strategy put forth by Rubio is that he would have U.S. special operation forces conduct bombings on ISIS training camps, and have the forces film these attacks in order to humiliate ISIS. Filming these attacks will show, according to Rubio, that ISIS members are not invincible, which would then cut off requirements and money.

TED CRUZ

At a press gaggle in Myrtle Beach, South Carolina, Ted Cruz, warned, “If we do not act on this terrorism, this violence will come to America.”

"There is no meaningful risk of Christians committing acts of terror," Cruz told reporters. "If there were a group of radical Christians pledging to murder anyone who had a different religious view than they, we would have a different national security situation."

“I call on Congress to pass the ex-Patriot Terrorist Act legislation I’ve introduced that says any American who joins ISIS to wage jihad against Americans they forfeit their citizenship. We will not allow jihadists to come back to America using U.S. passports to murder American men and women,” Cruz said.

Cruz wrote in a statement released Friday immediately after the Paris attacks that the United States should “consult with NATO allies who may be targeted for additional attacks.”

Later this afternoon, Cruz asked "who in their right mind" would bring Syrian refugees into the United States. "President Obama and Hillary Clinton's proposal to bring tens of thousands of Syrian refugees to America I think is absolute lunacy," he said.

MIKE HUCKABEE

During an interview with CNN, Huckabee called for closing our borders and creating a coalition to fight ISIS and al Qaeda. Huckabee said he’s open to using ground troops. "You can't exclude the possibility of ground troops,” he said.

JOHN KASICH

Ohio Gov. John Kasich called for a coalition to fight ISIS and no-fly zones.

In addition, Kasich has proposed invoking Article 5 of the North Atlantic Treaty. He posted to Facebook Sunday that Rubio and Graham “joined” him in calling for that. It is also something that Bush told MSNBC’s “Morning Joe” today “should be considered.”

RAND PAUL

“We should learn from the tragedy in Paris is that we have to be very careful and very cautious, extraordinarily cautious, about who comes to visit, who immigrates here and who studies here,” Paul said at the Florida GOP Sunshine Summit

Paul, who has argued against NSA surveillance of Americans, said he once tried to add an amendment to the 2013 “Gang of Eight” immigration bill.

“My amendment would have required fingerprint, background checks and extensive scrutiny of those who were coming to visit us,” Paul said.

CHRIS CHRISTIE

Speaking at the Florida GOP Party’s Sunshine Summit, Chris Christie said, “We must never allow this cult of evil to take hold in our country or to live amongst us. It is the antithesis of what it means to be a free American.”

CARLY FIORINA

“I am angry that President Obama unilaterally decides that we will accept in this nation 100,000 Syrian refugees while his administration admits that we cannot determine their ties to terrorism,” Fiorina said Saturday speaking at the Florida GOP Party’s Sunshine Summit, though Obama has vowed to accept only 10,000 in the next year.

Fiorina had started her remarks by expressing that she was “very angry” and “heartbroken by the carnage in Paris.”

“I am profoundly disappointed that our own president cannot speak with the same clarity of purpose as President Holland and Prime Minister David Cameron. Mostly though, I am angry. I am angry that just yesterday morning our president against all evidence declared ISIS contained and took a victory lap,” Fiorina said.

RICK SANTORUM, BOBBY JINDAL, LINDSEY GRAHAM, GEORGE PATAKI and JIM GILMORE

Rick Santorum said at a press availability following his speech to the Florida GOP Party’s Sunshine Summit that the United States needs “efficient boots on the ground to be effective in Iraq” and that he would "launching a major offensive against ISIS” to bomb ISIS back into the 7th Century.

Lindsey Graham said something similar this morning appearing with his friend Sen. John McCain on CNN’s “New Day.”

“Use the armies in the region which are large and professional. Integrate our forces among those armies with the French and other NATO nations. Have an air campaign supplemented by a ground campaign of 80 to 100,000 ground forces of which we’ll will be about 10 percent and going on the ground and destroy these people before they hit us here at home and continue to do damage,” said Graham, who believes another 9/11 will happen to America if action isn't taken.

ABC News' Ines De La Cuetara, Jordyn Phelps, Jessica Hopper and Ben Gittleson contributed to this report.