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Republican presidential candidates, from left, John Kasich, Carly Fiorina, Marco Rubio, Ben Carson, Donald Trump, Ted Cruz, Jeb Bush, Chris Christie, and Rand Paul take the stage during the CNN Republican presidential debate in Las Vegas. (AP) Republican presidential candidates, from left, John Kasich, Carly Fiorina, Marco Rubio, Ben Carson, Donald Trump, Ted Cruz, Jeb Bush, Chris Christie, and Rand Paul take the stage during the CNN Republican presidential debate in Las Vegas. (AP)

Republican presidential candidates, from left, John Kasich, Carly Fiorina, Marco Rubio, Ben Carson, Donald Trump, Ted Cruz, Jeb Bush, Chris Christie, and Rand Paul take the stage during the CNN Republican presidential debate in Las Vegas. (AP)

Lauren Carroll
By Lauren Carroll December 15, 2015
Jon Greenberg
By Jon Greenberg December 15, 2015
Louis Jacobson
By Louis Jacobson December 15, 2015
Linda Qiu
By Linda Qiu December 15, 2015
Katie Sanders
By Katie Sanders December 15, 2015
Amy Sherman
By Amy Sherman December 15, 2015

The Republican presidential candidates tangled over their approaches to defeating terrorism at home and abroad during the Las Vegas debate, their first matchup since the San Bernardino mass shooting.

Florida Gov. Jeb Bush and New Jersey Gov. Chris Christie pushed back against frontrunner Donald Trump’s proposed Muslim ban, and Sens. Marco Rubio, Ted Cruz and Rand Paul went back and forth over their views on immigration and government surveillance of Americans’ phone records. But several statements missed the mark on accuracy. (We'll update this story as we complete more fact-checks.)

The debate kicked off with a discussion over Trump’s controversial call to ban all Muslims from entering the United States. Many GOP candidates have criticized the proposal, including Cruz.

However, Cruz said, "everyone understands why Donald has suggested what he has," given President Barack Obama’s response to the terrorist attacks in California and Paris.

"President Obama and Hillary Clinton are proposing bringing tens of thousands of Syrian refugees to this country, when the head of the FBI has told Congress they cannot vet those refugees," Cruz said.

Cruz’s description of FBI director James Comey’s comments is inaccurate, so we rated the claim Mostly False.

In his testimony, Comey said he could not personally vet every refugee admitted to the United States (which would be required under a bill put forward by House Republicans). But he’s never said that the government cannot vet the refugees.

Comey has testified that there are challenges and risks to the screening process. But he’s also said the process is "effective," and we’ve gotten "dramatically" better at the task in the past few years.

Bush attacks Trump’s record on ISIS

Bush sparred with Trump throughout the night, calling the billionaire "a chaos candidate." At one point, Bush ridiculed Trump’s proposal to go after the families of terrorists as an unserious idea, further evidence, in Bush’s view, that Trump is incapable of thinking things through as commander-in-chief.

"Look, two months ago Donald Trump said ‘ISIS was not our fight,’ " Bush said.

Right away, Trump denied that he said such a thing. But Bush’s claim rates Mostly True.

The comments that fit within Bush’s time frame came on Sept. 28, 2015, when Trump sat for an interview with CNN’s Erin Burnett. Trump does appear to suggest that Russia and Syria should be the countries to primarily fight ISIS.

"Let Syria and ISIS fight. Why do we care?" Trump said. "And let Russia, they're in Syria already, let them fight ISIS."

Trump made comments closer to what Bush said about five months ago, in a July 8 interview with CNN’s Anderson Cooper. Trump used the words, "That’s not our fight," in describing the situation with ISIS.

"The situation with ISIS has to be dealt firmly and strongly. When you have people being beheaded — I would love not to be over there. That's not our fight. That's other people's fight. That's revolutions, that's whatever you want to call it, religious wars."

Rubio and an ‘open border’

During an intense and somewhat wonky debate over immigration, Cruz and Paul targeted Rubio as soft on amnesty for illegal immigrants and on protecting the border.

But one of Paul’s attacks received our worst rating.

"He thinks he wants to be this ‘Oh I am great and strong on national defense,’ " Paul said of Rubio, "but he is the weakest of all the candidates on immigration. He is the one for an open border that is leaving us defenseless."

The claim that Rubio "is for an open border" rates Pants on Fire.

Rubio co-authored a 2013 bill as part of the "Gang of Eight" that included billions of dollars for border enforcement and more border agents.

"If Sen. Rubio was really for open borders, the Gang of Eight bill wouldn't have been 1,198 pages long while doubling the size of border patrol," said Alex Nowrasteh, an expert on immigration at the libertarian Cato Institute.

After the bill died, Rubio has repeatedly said border security needs to be beefed up. Paul’s claim is inaccurate and ridiculous.

Fiorina and the generals  

Former Hewlett Packard CEO Carly Fiorina hit both Obama and her Republican rivals in one answer on how she would defeat ISIS.

"To wage war, we need a commander in chief who has made tough calls in tough times and stood up to be held accountable over and over, not first-term senators who've never made an executive decision in their life," Fiorina said. "One of the things I would immediately do, in addition to defeating them here at home, is bring back the warrior class -- Petraeus, McChrystal, Mattis, Keane, Flynn. Every single one of these generals I know. Every one was retired early because they told President Obama things that he didn't want to hear."

Her claim rates Mostly False.

Fiorina was on solid ground with two of her examples: Gen. James Mattis and Lt. Gen Flynn. But she’s off the mark with the others.

Even though there was friction between Gen. Stanley McChrystal and the Obama administration over policy, McChrystal was removed from his post after he and his staff were quoted making disparaging remarks about Vice President Joe Biden and others in Rolling Stone.

Gen. David Petraeus’ resignation had nothing to do with policy — he shared classified documents with a woman with whom he was having an affair. Gen. John Keane resigned in 2003, six years before Obama took office.

Rubio: Cruz supports 'legalizing' illegal immigrants

In a juicy moment from the Rubio-Cruz showdown, Rubio tried to portray Cruz as being soft on immigration policy, which Cruz immediately denied as true.

"Ted, you support legalizing people who are in this country illegally," Rubio said. "Ted Cruz supported a 500 percent increase in the number of H1B visas, the guest workers that are allowed in this country. And Ted supports doubling the number of green cards."

The claim that Cruz supports legalizing people who are here illegally rates Mostly False.

Cruz proposed an amendment in 2013 to the immigration bill that would have stripped the citizenship provision. But it would have kept intact the language in the Senate bill that allowed illegal immigrants to still apply for the Registered Provisional Immigrant program in the overall bill, which would have resulted in a work permit and 10 years later application for permanent residency.

But it’s a stretch for Rubio to label Cruz as a supporter of legalization when he was an ardent critic of the overall bill for months and voted against it.

So what's carpet-bombing, anyway?

Moderator Wolf Blitzer tried to pin down Cruz on his controversial "carpet bombing" proposal to deal with ISIS, asking Cruz if he means he wants to carpet-bomb the civilian-heavy ISIS capital of Raqqa, "yes or no?"

Cruz responded, "You would carpet bomb where ISIS is -- not a city, but the location of the troops. You use air power directed -- and you have embedded special forces to direction the air power. But the object isn't to level a city. The object is to kill the ISIS terrorists."

But there’s a problem: What Cruz described isn’t carpet bombing. What he described is actually the opposite of carpet bombing, so we rated his explanation False.

The defining characteristic of carpet bombing is that it’s indiscriminate -- not targeted. The first use of the term dates to around World War II, when Allied strikes during and following the invasion of Normandy killed an estimated 40,000 French civilians. Later in the war, a three-day, joint U.S.-British attack on Dresden, Germany, stirred up monumental fires that killed more than 125,000 people. And in Tokyo, a March 1945 attack using six tons of incendiary bombs burned almost 16 square miles and killed more than 80,000 people. Other examples from the Korean War and the Vietnam War are sometimes cited.

Given the downsides of carpet bombing -- especially large civilian casualties, which don’t reflect well on the bombing nation in a media-interconnected world -- it’s not a military tactic used often today. For one thing, it’s arguably outlawed by the 1977 Additional Protocols to the Geneva Conventions. But the more important factor is that today’s precision-guided "smart" bombs and delivery systems provide better targeting without any loss in explosive power.

The World War II examples of indiscriminate attacks were undertaken "because more precise bombing was not possible," said John Pike, the director of "The U.S. tried precision daylight bombing where they tried to hit individual factories, but they were too vulnerable to enemy fighters and anti-aircraft artillery, so they joined the Royal Air Force in burning down German cities at night."

Surveillance then and now

Another topic where Rubio and Cruz clashed: the government’s bulk phone data collection program.

The domestic surveillance program allowed the National Security Agency to secretly access the metadata of millions of phone calls; it was made public by government contractor Edward Snowden. Congress curtailed the program and it officially shut down just days before the San Bernardino terrorist attack. Rubio says it has limited the government’s ability to fight terrorism.

On the debate stage, Cruz defended his vote for the USA Freedom Act, saying it not only respects civil liberties by stopping the government from automatically collecting bulk data, but it also expands the government’s ability to gather terrorists’ phone records.

"The old program covered 20 to 30 percent of phone numbers to search for terrorists," Cruz said. "The new program covers nearly 100 percent. That gives us greater ability to stop acts of terrorism, and he knows that’s the case."

Rubio responded, "Let me be very careful when answering this, because I don’t think national television in front of 15 million people is the place to discuss classified information, so let me just be very clear: There is nothing we are allowed to do under this bill that we could not do before."

That’s a pretty stark difference --- Cruz says we’ll have access to many more phone numbers, and Rubio says this bill doesn’t do anything new. We decided to focus on Rubio’s statement.

It rates Half True.

Whereas the old bulk phone data collection program wasn’t very good at collecting cell phone and Internet phone records, the Freedom Act establishes parameters that make this more feasible. However, it’s not like the government couldn’t access these records at all before, they just couldn’t do it through the bulk collection program. The law did not give the government a brand-new legal authority, it just helps to streamline the record collection process.

Trump and the Geneva Conventions

Trump got a challenge on an earlier statement this month that the United States should be killing families of terrorists. CNN aired a pre-recorded question from Josh Jacob, a student at Georgia Tech: "Recently Donald Trump mentioned we must kill the families of ISIS members. However, this violates the principle of distinction between civilians and combatants in international law."

Trump doubled down on his position: "I would be very, very firm with families" and repeating his sentiment that even though people think "they may not care much about their lives … they do care, believe it or not, about their families' lives."

Later in the debate, Paul took Trump to task for that approach.

"If you are going to kill the families of terrorists," Paul said, "Realize that there's something called the Geneva Convention we're going to have to pull out of. It would defy every norm that is America."

We rated Paul's claim True.

The Geneva Conventions were designed after World War II to establish agreed-upon rules of war. The United States, like most countries, is a party to them and "is hugely committed in principle and in the training of soldiers," said Steven R. Ratner, a University of Michigan law professor.

According to Common Article 3, people who are taking no active part in the hostilities "shall in all circumstances be treated humanely… To this end, the following acts are and shall remain prohibited at any time and in any place whatsoever … violence to life and person, in particular murder of all kinds, mutilation, cruel treatment and torture."

Experts said this language would make Trump’s approach a violation of the Geneva Conventions, assuming that the family members were not taking part in terrorist activities.

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