Republican debate as it happened: GOP candidates face off for the fifth time in Las Vegas

That's a wrap! The next debate, with the three Democratic candidates, will be held on 19 December.

The candidates make their closing statements:

• Paul: Claims the greatest threat to the US is its national debt. Blames both parties and says he will reign in spending.
• Kasich: Discusses what is needed to win Ohio in the upcoming election. Says Republicans will be able to beat Clinton.
• Christie: Talks about his time as state prosecutor and how his family experienced the 9/11 attacks. He says as president he would protect America from wars being brought to "our doorsteps".
• Fiorina: Also brings up 9/11 attacks and the actions she took following the terrorist attack. She takes aim at Clinton and the "political class". Says the US needs a real conservative in the White House.
• Bush: Calls on voters to ask themselves who would be able to protect them better, him or Clinton? He says he delivers results.
• Rubio: Says the 2016 election is crucial in determining the future of the US. Says with votes, the US will be rebuilt.
• Cruz: Recalls Reagan's successes and says he will do the same. Says he has a simple strategy: "We win, they lose".
• Carson: Talks about his mother and says he is not ready
• Trump: "We have to change our whole way," he says. Claims if he's elected, "We will win again."

A top financial expert warns that Trump's populist economic policies could end up hurting American consumers and potentially destablise the global economy.

"It is alarming that the most visible and recognisable GOP candidate seems to be using his more sensible policies to disguise the more ill-conceived ones; ones that potentially threaten the US, and, therefore, the global economy," Green told IBTimes UK.

"For instance, Trump's immigration policy is achingly naive. If it were enforced, the labour force would shrink and real GDP would fall. Both supply and demand would be affected.

Trump confirms that he is ready to not run as an Independent and says he is "committed" to the Republican Party.

Fiorina faces a question on North Korean leader Kim Jong-un. She says that the US should work with China on North Korea and that the country should remain isolated.

Christie is asked a Facebook question: Doesn't the Bible teach us to take in refugees?

The New Jersey governor responds: The first job of the president is to protect your safety and your security.

An October survey by the Pew Research Center looked into whether undocumented immigrants should be allowed to stay legally in the US. Opposition for immigrants staying broke down as follows:

• 17% of Democrats
• 32% of Republicans

Meanwhile, the percentage of those who believe undocumented immigrants should be allowed to stay legally represent the majority.

• 80% of Democrats
• 66% of Republicans

The debate turns to immigration. Cruz and Rubio go at each other again. Rubio is in favour of providing a tough path to citizenship, Cruz says he is not and never will be in favour of providing a path to citizenship. Trump, meanwhile, maintains his proposal to deport the estimated 11 million undocumented immigrants in the US.

Trump has his moment to complain about how he is being treated.

Talk turns to Russia and its involvement in Syria. Christie calls Obama a "feckless weakling" when talking to a proposed no-fly zone over Syria. He's asked whether he would shoot down a Russian plane in said no-fly zone. "Yes we would shoot down the planes of Russian pilots if they were stupid enough to think that this president is the same feckless weakling that we have in the White House," he said.

Trump is asked if the Middle East is better off with dictators in power. "It's not like we had victory," he says. "It's a mess." He's interrupted by a heckler and several boos.

Cruz and Rubio are back at each other again. Cruz is asked about supporting Hussein, Qaddafi and Mubarak while they were in power. "I believe in an America-first foreign policy," Cruz says. He says that the US needs to learn from history and that if Bashar al Assad is toppled, Syria will be overtaking Isis. Rubio says Qaddafi was responsible for Lockerbie and the Berlin cafe bombing of Marines. Kasich jumps in and says Assad must go.

Margaret Thatcher once said, 'If you want something talked about, ask a man. If you want something done, ask a woman.'

- Carly Fiorina

It's Paul's turn to take aim at GOP frontrunner Trump for his proposals to close up the Internet and kill off the family members of terrorists. "Think, do you believe in the Constitution? Are you going to change the constitution?" Paul asks Trump. The bombastic real estate mogul responds, "So they can kill us, but we can't kill them?"

Cruz and Rubio get at each other, with Rubio attacking Cruz's voting record regarding cuts on the military. They're followed up by a rumble between Trump and Bush, after Trump is asked how his comments about killing the families of terrorists make him any different than Isis.

Cruz is questioned about his comments on carpet-bombing Isis and whether he would bomb Raqqa, which not only is the capitol of the Islamic State but has thousands of civilians. He deflects and says he would not carpet bomb a city but an area Isis is in control of.

Trump is asked about closing the Internet. He says he wants to rely on Silicon Valley to figure out how to stop Isis from using "our Internet" to recruit young people. He also wants to use "our good people" to "penetrate" Isis. He adds he would be open to closing up parts of the Internet.

Bush is asked about his brother's comments as president that Islam is a religion of peace and whether that is still relevant. "They are relevant if we want to destroy Isis... we can't disassociate ourselves from peace-loving Muslims," he says.

Carson is asked about his position on monitoring mosques with "anti-American" sentiments. He uses his time to first complain about not having enough speaking time and then saying the US should stop being afraid of being politically correct.

When asked who he thinks was right, Rubio or Paul, he deflects.

Paul and Rubio go head to head on the NSA's surveillance programme and immigration policy. Paul attacks Rubio's stance on immigration for allowing potentially dangerous individuals into the US. Rubio notes that the San Bernardino shooter was a US-born citizen and it would have been helpful to have the NSA's programme to weed him out.

Kasich is asked how find an attacker, like Syed Farook, who is an American citizen not on a terror watch list. He says the US must destroy Isis and takes a jab at the Paris climate talks.

Christie is asked about the hoax terror threat sent in Los Angeles and New York City and whether its the new normal. He says that it is indeed the "new normal" under President Obama and will continue if Clinton is elected.

Rubio is asked about a poll showing a majority of Republican voters supporting Trump's proposed ban on Muslims. He says he understands why voters feel that way and goes on to describe how Isis has grown. "The president has left us unsafe," Rubio adds.

Bush is asked about his comment calling Trump "unhinged". He says that the fight against Isis must be done with the help of Muslim countries. Says that Trump is a chaos candidate and would be a chaos president if he were elected.

Trump claims that Bush does not actually believe he is "unhinged" but said that because his campaign is failing.

First question goes to Trump about his comments regarding his proposed ban on Muslims and wanting to build a wall in the southern boarder. Trump says he is not talking about isolation but security, not about religion but security.

The nine candidates have one minute to introduce themselves.

• Rand Paul takes his minute to hit Trump, comparing him to China and North Carolina, and Rubio.
• John Kasich calls for all Americans to unite, whether they are Republicans or Democrats.
• Chris Christie brings up the hoax threat in Los Angeles and attacks Obama and Clinton for not protecting Americans.
• Carly Fiorina, who has had success in past debates, recalls her successes, including beating breast cancer and becoming a business leader.
• Jeb Bush calls for restoring the military and taking money away from Washington and giving it to American families.
• Marco Rubio takes aim at Obama, says if he's elected, he will be a president who believes the US is the greatest country on Earth.
• Ted Cruz says the US is at war with radical Islamic terrorism. Says if he's elected, the US will "utterly destroy" Daesh.
• Ben Carson uses his time to call for a moment of silence for the victims of the San Bernardino shooting. Asks Congress to declare war on Isis.
• Donald Trump claims he "opened up a discussion" that "needed to be opened" in regards to terrorism.

And we're back for the main event. The candidates are heading towards the stage. Important to note: New Jersey Governor Chris Christie is back in the main debate after being downgraded to the undercard debate in November.

Coming up is the main debate. Here is where the nine candidates stand in the latest ABC News/The Washington Post national poll among Republican voters:

• Donald Trump: 38%
• Ted Cruz: 15%
• Ben Carson: 12%
• Marco Rubio: 12%
• Jeb Bush: 5%
• Chris Christie: 4%
• John Kasich: 2%
• Rand Paul: 2%
• Carly Fiorina: 1%

The candidates give their closing statements:

• Graham says he is ready to be president. "Events have proven me more right than wrong. We've spent a lot of carnage to getting where I have always been. Make me president."
• Pataki noted the debate was about terrorism and discussed his time as governor of New York during 9/11. Calls on everyone to visit lower Manhattan to see the Freedom Tower
• Santorum went on the attack against President Obama and Democratic frontrunner Hillary Clinton. He hits against Daesh, adding, "I know the face of evil and I will defeat it."
• Huckabee said that terrorist do not win because they kill people, but because they scare people. "I want my grandkids to grow up not in fear but in faith and freedom," he said.

Heading off to a quick break, before the first undercard debate begins to wrap up.

The debate turns to the refugee crisis:

Santorum says that the US can vet incoming refugees, just not those from Syria.

Pataki says he would not allow any Syrian refugees into the US. Calls for more refugee camps in the Middle East. Recalls the 9/11 attacks in New York City.

It should be noted that there has been no terrorist attack in the US attributed to the current Syrian refugee crisis.

Candidates are sparring on whether women should serve in the military in combat positions. Santorum appears to be against women in combat roles, while Pataki and Graham are in favour.

The candidates are asked whether they would reinstate the draft in the US. Graham is vehemently opposed to the draft. "If you don't want to be there, I don't want you there," he says. While Huckabee says he's also opposed to the draft, he adds he wants "to ask people to recognize that we are at war."

These people are religious Nazis. Most people in Islam don't buy what they're selling.

- Lindsey Graham

The senator went on to quote The Princess Bride to make a jab at Texas Senator Ted Cruz for saying he could be open to leaving Bashar al Assad in power in Syria.

The conversation moves slightly towards Syria's Bashar al Assad and Russia's Vladimir Putin. Huckabee says that he would not support al Assad's reelection bid but he prefers him in power because while he killed many, none were American.

Pataki, like Graham, says he believes the US should send troops to Syria. "We have to send troops with allies and supporters wherever it is necessary to destroy the training centers and recruitment centers of Isis," he says. He does not, however, give any specifics.

Huckabee also wants to advocate sending troops to Syria. Particularly young troops.

Santorum declares that while he supports boots on the ground in Iraq, he does not support American troops in Syria. He later says he would be open to training troops in Syria, but not fighting.

Graham is asked how he would defeat Daesh online and he discusses his military plan. "What you want to do is you want to knock them offline," Graham says. He adds he is "seeking victory, folks, not containment."

"There are at least 3,500 Muslims serving in the armed forces. Thank you for your service. You are not the enemy. Your religion is not the enemy.

- Lindsey Graham

The debate turns to the second Amendment and the debate over whether individuals on terror watch lists should be allowed to purchase guns.

While the candidates largely seem against Trump's proposal to ban Muslims from entering the US, they appear ready to monitor mosques and imans that are reportedly attempting to radicalise Americans, as Trump also proposed.

As usual, Graham calls for boots on the ground in the Middle East as well as the mass collection of phone data. He calls the fight against terrorism a "religious war".

Santorum, unlike the previous two candidates, attempts to justify Trump's proposal, saying he did not mean to attack Islam. He says that while he supports the religious liberties of Muslims in the US, the fight against Daesh is crucial. "The fact is, not all Muslims are jihadists. But the reality is, all jihadists are Muslims," he says.

Pataki also goes against the GOP frontrunner, calling him the "No Nothing" candidate. He calls Trump's proposed ban as "un-American" and "absurd".

The candidates are asked about Donald Trump's controversial proposal to ban all Muslims from temporarily entering the US. Graham attacks Trump for doing precisely what Daesh wants, declaring war against Muslims.

Each candidate will get one minute to introduce themselves.

Graham: The senator, who is the first to go, tells a story about his recent trip to Iraq and an interaction with a special forces member.

Pataki: The former governor brings up the terror scare in Los Angeles, which forced the closure off all schools in the district. He then goes on the attack against Democrats.

Santorum: The former senator declares the US has entered World War III, placing the blame squarely on President Barack Obama. He blames Obama for the Iran deal and for the rise of Isis (Daesh).

Huckabee: The former governor is the first to bring up the San Bernardino shooting and the failure to capture shooter Tashfeen Malik before the attacks.

The four GOP candidates take the stage for the official start of tonight's undercard debate.

The undercard debate, which is set to begin in mere minutes, will see a return of Senator Lindsey Graham and former Governor George Pataki. Both failed to make the cut for the previous debate. Expect Graham to shine with the debate's focus on national security. Graham has in the past declared his intentions to go war with the Islamic State (Isis).

Just hours ahead of participating of the undercard debate, Mike Huckabee released a video on Twitter taking a jab at Washington DC, which he calls the "Vegas of the east".

The undercard debate is still minutes away from beginning. To watch or listen to the debate, CNN will air it live and stream online on CNN.com. The network will also make the debates available through mobile live stream on its mobile app. Users will need to select "Watch Live TV" on the mobile app to watch on their phones. Those who wish to listen to the debates instead can tune in to any Salem Network broadcast across the US.

CNN has revealed the format of the debates tonight. Each candidate has 75 seconds to answer questions and 30 seconds to respond if named. This is slightly more time than in previous debates, where candidates were given just 60 seconds to answer questions. The topic of the night will be national security, which is relevant given the recent San Bernardino shooting.

The undercard debate will be crucial in potentially weeding out candidates as the election gets closer to the primary elections. Louisiana Governor Bobby Jindal, who was downgraded to the undercard debate in November, dropped out of the race shortly after the debate.

The undercard debate is set to air in a few minutes, featuring the bottom four candidates of the Republican Party. The latest poll by ABC News/The Washington Post reveal the bottom for stand as follows among Republican voters:

• Mike Huckabee: 1%
• Rick Santorum: less than 0.5%
• Lindsey Graham: 1%
• George Pataki: 0%