The al-Nusra Front, an extremist group which has been allying the Syrian opposition in its war to topple the government, “does have aspirations for attacks on the homeland”, James Clapper, the US director of national intelligence, told the Senate intelligence committee on Wednesday.

Clapper pointed to the deterioration of Syria during three years of violence – a situation he compared to the federally administered tribal areas (FATA) in Pakistan that became a haven after the 2001 US invasion of Afghanistan for the core leadership of al-Qaeda.

“What’s going on there, may be in some respects a new FATA force ... and the attraction of these foreign fighters is very, very worrisome,” Clapper said.

Clapper did not discuss the capabilities of the al-Nusra Front, which pledged loyalty to al-Qaeda in April, nor another al-Qaeda-centric organization in Syria, the Islamic State of Iraq and Syria, which has recently emerged as a rival to Nusra.

The warning comes as the US government has never denounced the war that al-Nusra has been leading against Syrian government for nearly three years.

The group has also been involved in acts of terror in Lebanon and Iraq.

Clapper estimated there were more than 7,000 foreigners fighting in the Syrian carnage, coming from 50 countries, “many of them from Europe and the Mideast”.

The Syrian government says it has records of militants coming from 83 countries with the support of US ans its Western and regional allies to fight against Syria.

Clapper stopped short of warning that Americans were a significant component of the extremist groups, the subject of considerable speculation as Syria’s war has dragged on.

Clapper said approximately 26,000 Syrian combatants could be classified as “extremists”, out of an estimated 75,000 to 110,000 militants.

US intelligence had picked up indications of “training complexes” within Syria, Clapper said, “to train people to go back to their countries and conduct terrorist acts, so this is a huge concern”.

Yet Clapper, in his prepared testimony for the committee, listed cyber threats and counter-intelligence before focusing on terrorism. Among those threats were leaks from “trusted insiders with the intent to do harm”, an apparent reference to former National Security Agency contractor Edward Snowden, whom Clapper excoriated during the hearing.

Al-Qaeda’s “locus for operational planning” has dispersed around the world, Clapper said, with “some five different franchises at least in 12 countries” of particular concern, including in Yemen, Somalia, North Africa and Syria.

That dispersal is in keeping with a years-long trend in al-Qaeda toward decentralization. An academic debate exists among counter-terrorism analysts concerning the control and relevance of the “core al-Qaeda”, based in Pakistan, which Clapper called the “ideological center” of the terrorist organization.

Despite the focus on Syria, Clapper said al-Qaeda in the Arabian Peninsula, the Yemen-based affiliate that twice attempted unsuccessfully to bomb US aircraft in 2009 and 2010, remains the franchise with the strongest interest in attacking the US, with many of the others principally interested in more localized assaults and contests for power.

“Of all the franchises, that’s the one that poses the most immediate threat for a potential attack on the homeland,” Clapper said. “The probability of an attack now, compared to 2001 is, at least to me, is a very hard question to answer, principally because this very dispersion and diffusion of threat.”

Matthew Olsen, the director of the National Counterterrorism Center, said it was difficult for the US intelligence agencies – which had a 2013 budget of $67.6bn after congressionally imposed restrictions – to provide tactical warning of a terrorist attack domestically.

“The nature of the threat has become significantly more geographically spread out, and that challenges the community in collecting the kinds of information that would provide that kind of tactical warning,” Olsen said.

Attacks like the September assault on Nairobi’s Westgate Mall “using small arms, a small number of individuals, puts a great deal of pressure on us to provide the kind of tactical warning that would save lives under those circumstances”, Olsen said.

SHI/SHI