They are powerless from stopping them even though they've been

The Director of the FBI has warned the Khorosan terror group will strike the US 'very very soon' and says Americans fighting alongside militants in Syria cannot be stopped from returning home.

J ames Comey said the unit of Al Qaeda veterans are 'bent on destruction' and are believed to be working on an attack directed at the United States or its allies.

However he assured the public by saying changes made since 9/11 mean the security services are 'better in every way that you'd want' and have the systems in place to quash any threat.

Scroll down for video

Concerns: FBI Director James Comey said the Khorosan terror group could attack 'very very soon' and admitted that Americans fighting alongside militants in the Middle East are entitled to return

Speaking on CBS 60 Minutes, he confirmed that there are around a dozen American citizens fighting in the Middle East for the extremist groups, and the government is aware of who they are.

The interviewer Scott Pelley asks: 'How many Americans are fighting in Syria on the side of the terrorists?'

'In the area of a dozen or so,' Comey replied.

'Do you know who they are?'

Comey answers: 'Yes.'

Pelley then pressed: 'Each and every one of them?'

'I think of that, dozen or so, I do. I hesitate only because I don't know what I don't know,' Comey said.

He said: 'Ultimately, an American citizen, unless their passport's revoked, is entitled to come back. So, someone who's fought with ISIL, with American passport wants to come back, we will track them very carefully.'

Discussing the US fight against terrorism, Comey added that the terrorist networks within Syria as a sophisticated 'metastasis' of Al Qaeda

Khorosan, a small group of Al Qaeda veterans from Afghanistan and Pakistan, was targeted in strikes near Aleppo, Syria, last month. Senior U.S. officials have not said whether the group's plots have been disrupted.

Comey said: 'Given our visibility we know they're serious people, bent on destruction.'

But he added that Americans should have confidence in changes made since the Sept. 11, 2001, terrorist attacks, pointing to a government 'better organized, better systems, better equipment, smarter deployment. We're better in every way that you'd want us to be since 9/11.'

During the interview, he also compared Chinese hackers to a 'drunk burglar' who steals with reckless abandon, even as they cost the U.S. economy billions of dollars every year.

Questioning: When interviewer Scott Pelley asked Comey whether he knew who the Americans fighting with the extremists were, he replied simply saying 'Yes'

In an interview broadcast Sunday on CBS' '60 Minutes,' Comey said Chinese hackers target the intellectual property of U.S. companies in China every day.

'I liken them a bit to a drunk burglar. They're kickin' in the front door, knocking over the vase, while they're walking out with your television set. They're just prolific. Their strategy seems to be: `We'll just be everywhere all the time. And there's no way they can stop us,'' Comey said.

The Justice Department earlier this year announced a 31-count indictment against Chinese hackers accused of breaking into computer networks at steel companies and the manufacturers of solar and nuclear technology, with the goal of gaining a competitive advantage. China has denied the allegations.

Comey admitted that the government knows the citizens who have travelled to join the fighting and will 'track them very carefully' if they return

In the CBS interview, Comey also discussed the U.S. fight against terrorism. He described the terrorist networks within Syria as a sophisticated 'metastasis' of al-Qaida.

He said the Khorasan Group, an al-Qaida cell in Syria that was targeted in military strikes last month, was 'working and, you know, may still be working on an effort to attack the United States or our allies, and looking to do it very, very soon.'