Newt Gringrich has admitted Donald Trump does not yet have a plan to defeat Isis - despite the President-elect boasting that he would defeat the terror group “very, very quickly”.

The former Republican House Speaker, who informally advises Trump, said he did “not think they had a strategy” but was confident that “they know, which is important, is that they are gonna need a strategy”.

Despite this, Mr Gingrich told Fox News he was confident that Mr Trump’s security advisory team - which includes several retired generals - would come up with an “aggressive” action plan.

He said: “They are going to be able to produce a very aggressive strategy. They have a much better grip on reality than the Obama administration did”.

This is a markedly different tone from the confident bluster of the campaign trail where Mr Trump said Isis' “days are numbered” but refused to divulge his plan for fear of the terror group hearing about it.

In April, the former reality star said: “If I am elected President, Isis will be gone and they will be gone quickly. Very, very quickly.

“I won’t tell them where and I won’t tell them how. We must as a nation be more unpredictable.

Donald Trump reacts to Berlin attack

“Containing the spread of radical Islam must be a major foreign policy goal of the United States and indeed the world.”

Mr Gingrich said one of the ways Mr Trump could fight back against extremism would be to suspend civil liberties - which he claims Abraham Lincoln did during to the American Civil War.

He said: “People should go back and look at how Lincoln dealt with Southern sympathisers during the Civil War.

“We passed a Sedition Act for example, which changed our ability to control people who were advocating treason.”

Donald Trump's most controversial quotes Show all 14 1 /14 Donald Trump's most controversial quotes Donald Trump's most controversial quotes On Isis: "Some of the candidates, they went in and didn’t know the air conditioner didn’t work and sweated like dogs, and they didn’t know the room was too big because they didn’t have anybody there. How are they going to beat ISIS?" Getty Donald Trump's most controversial quotes On immigration: "I will build a great wall — and nobody builds walls better than me, believe me —and I’ll build them very inexpensively. I will build a great, great wall on our southern border, and I will make Mexico pay for that wall. Mark my words." Reuters Donald Trump's most controversial quotes On Free Trade: "Free trade is terrible. Free trade can be wonderful if you have smart people. But we have stupid people." PAUL J. RICHARDS | AFP | Getty Images Donald Trump's most controversial quotes On Mexicans: "When Mexico sends its people, they’re not sending their best. They’re sending people that have lots of problems. They’re bringing drugs. They’re bringing crime. They’re rapists." Getty Donald Trump's most controversial quotes On China: "I just sold an apartment for $15 million to somebody from China. Am I supposed to dislike them?... I love China. The biggest bank in the world is from China. You know where their United States headquarters is located? In this building, in Trump Tower." Getty Images Donald Trump's most controversial quotes On work: "If you're interested in 'balancing' work and pleasure, stop trying to balance them. Instead make your work more pleasurable." AP Donald Trump's most controversial quotes On success: "What separates the winners from the losers is how a person reacts to each new twist of fate." Donald Trump's most controversial quotes On life: "Everything in life is luck." AFP Donald Trump's most controversial quotes On ambition: "You have to think anyway, so why not think big?" Getty Images Donald Trump's most controversial quotes On his opponents: "Bush is totally in favour of Common Core. I don't see how he can possibly get the nomination. He's weak on immigration. He's in favour of Common Core. How the hell can you vote for this guy? You just can't do it." Reuters Donald Trump's most controversial quotes On Obamacare: "You have to be hit by a tractor, literally, a tractor, to use it, because the deductibles are so high. It's virtually useless. And remember the $5 billion web site?... I have so many web sites, I have them all over the place. I hire people, they do a web site. It costs me $3." Getty Images Donald Trump's most controversial quotes On Barack Obama: "Obama is going to be out playing golf. He might be on one of my courses. I would invite him. I have the best courses in the world. I have one right next to the White House." PA Donald Trump's most controversial quotes On himself: "Love him or hate him, Trump is a man who is certain about what he wants and sets out to get it, no holds barred. Women find his power almost as much of a turn-on as his money." Getty Images Donald Trump's most controversial quotes On America: "The American Dream is dead. But if I get elected president I will bring it back bigger and better and stronger than ever before and we will make America great again." GETTY

Historians say Lincoln did not pass a specific law tackling dissent but he did suspend several First Amendment freedoms such as Habeas Corpus - the right to a speedy trial.

Following his victory in the Electoral College last month, the Muslim registry was one of several outlandish pledges - including the infamous wall on the Mexican border - he appeared to have backtracked on.

But after an attack where Anis Amri ploughed a stolen lorry into the crowd at a Christmas market in west Berlin, killing 12 people, Mr Trump renewed his registry pledge saying: “It’s an attack on humanity and it’s got to be stopped”.

It is still unclear how Mr Trump will be able to put this idea into practice without violating the US Constitution but the Council on American-Islamic Relations reported at least 900 hate crime incidents against Muslims in the weeks after the election.