Best Lines of the Final GOP Debate of 2015

— -- The Republican debate on Tuesday night hosted by CNN in Las Vegas included nine presidential candidates, welcoming New Jersey Gov. Chris Christie back to the main debate stage.

The final debate of 2015 focused on national security and terrorism -- and as per usual, wasn't short of one-liners.

Here are the best lines of the final Republican debate:

ON DONALD TRUMP'S PROPOSAL TO BAN MUSLIMS FROM ENTERING THE US

TRUMP: "We are not talking about isolation. We're talking about security. We're not talking about religion. We're talking about security. Our country is out of control. People are pouring across the southern border. I will build a wall. It will be a great wall."

BUSH: "Well, first of all, we need to destroy ISIS in the caliphate. That should be our objective. The refugee issue will be solved if we destroy ISIS there."

"So, Donald, you know, is great at the one-liners. But he's a chaos candidate. And he'd be a chaos president. He would not be the commander-in-chief we need to keep our country safe," Bush added.

Trump fired back: "Jeb doesn't really believe I'm unhinged. He said that very simply because he has failed in this campaign. It's been a total disaster. Nobody cares. And frankly, I'm the most solid person up here."

CLIMATE OF FEAR

CHRISTIE: “Everywhere in America is a target for these terrorists.”

ON USA FREEDOM ACT

CRUZ: “I'm very proud to have joined with conservatives in both the Senate and the House to reform how we target bad guys,” Cruz responded when asked if his vote for a bill that President Obama signed into law making it harder for the government to access Americans’ phone records.

"It gave us greater tools and we are seeing those tools work right now in San Bernardino. In particular, what it did is the prior program only covered a relatively narrow slice of phone calls," Cruz added.

RUBIO: “We are now at a time when we need more tools and not less tools. That tool we lost: the metadata tool. That was a valuable tool that we no longer have at our disposal.”

Cruz argued, “I would note that Marco knows what he's saying isn’t true.”

PAUL: "You know, I think Marco gets it completely wrong. We are not any safer through the collection of all Americans' records. In fact, I think we're less safe."

RUBIO: "If a regular law enforcement agency wants your phone records, all they have to do is issue a subpoena. But now the intelligence agency is not able to quickly gather records and look at them to see who these terrorists are calling."

SHUTTING DOWN THE INTERNET

TRUMP: "They shouldn't be using the word mastermind. These are thugs and terrible people in ISIS. Not masterminds."

"I would certainly be open to closing areas where we are at war with somebody. I sure as hell don't want to let people that want to kill us and kill our nation use our Internet," Trump added.

Paul in response to Trump, "Are you going to change the constitution?"

KASICH: "No. I don't think it is [a good idea]."

CRUZ: "The problem is because of political correctness, the Obama administration, like a lot of folks here, want to search everyone's cell phones and emails and not focus on the bad guys, and political correctness is killing people."

CRUZ-RUBIO SHOWDOWN

CRUZ: "One of the problems with Marco's foreign policy is he has far too often supported Hillary Clinton and Barack Obama undermining governments in the Middle East that have helped radical Islamic terrorists. We need to focus on killing the bad guys, not getting stuck in Middle Eastern civil wars that don't keep America safe."

RUBIO: "If you're an American citizen and you decide to join up with ISIS. We're not going to read you your Miranda rights. You're going to be treated as an enemy combatant a member of an army attacking this country."

ON TRUMP'S FOREIGN POLICY EXPERIENCE

BUSH: "He gets his foreign policy experience from the shows. That is not a serious kind of candidate. We need someone that thinks this through. That can lead our country into safety and security."

Trump responded: "I know you’re trying to build up your energy, Jeb, but it’s not working. We need a toughness. We need strength."

BUSH: "Donald, you're not going to be able to insult your way to the presidency. That's not going to happen."

TRUMP: "With Jeb's attitude, we will never be great again. That I can tell you. We will never be great again."

ON DICTATORS RUNNING THE MIDDLE EAST

TRUMP: "We have spent $4 trillion trying to topple various people. ... I wish we had the $4 trillion ... wish it were spent right here in the United States on schools, hospitals, roads, airports and everything else that are all falling apart."

Fiorina in response: "That's exactly what President Obama has said. I'm amazed to hear that from a Republican presidential candidate."

CARSON: "But there comes a time when you're on an airplane, they always say, in case of an emergency, oxygen masks will drop down put yours on first and administer help to your neighbor. We need oxygen right now and need to think about the needs of the American people before we go and try to solve everybody else's problems."

ON SHOOTING DOWN RUSSIAN PLANES.

CHRISTIE: "I would do it."

KASICH: "It is time we punched the Russians in the nose."

PAUL: "When we think about the judgment of someone who might want World War III we might think about someone who would shut down a bridge because they don't like their friends. I think we need to be very careful about that."

ON THE MEDIA

TRUMP: "I think it's very sad that CNN leads Jeb Bush down a road by starting all the questions Mr. Trump this, Mr. Trump that, I think it's very sad."

ON IMMIGRATION

RUBIO: "I am personally open, after all that has happened and after ten years in probationary status, I am open to a green card."

CRUZ: "Border security is national security."

"If I'm elected president, we will secure the border. We will triple the border patrol. We will build a wall that works and I'll get Donald Trump to pay for it," Cruz added.

Trump responded, "I'll build it."

TRUMP: "We either have a border or we don't."

ON CRUZ'S LEAKED AUDIO OBTAINED BY THE NEW YORK TIMES.

Trump to Cruz: "You better not attack."

Cruz: "All nine of the people here would make an infinitely better commander-in-chief than Barack Obama or Hillary Clinton."

ON RUNNING FOR A THIRD PARTY

TRUMP: "But I will tell you, I am totally committed to the Republican Party."

CARSON: "The statement that I would leave the party was contingent upon whether in fact the party acts like they have in the past with a lot of subterfuge."