The US government believes there are 20 to 30 Americans currently fighting in Syria for the panoply of jihadist groups there, according to a senior official.



The estimate is less than an earlier and much-quoted assessment of approximately 100 Americans taking part in Syria’s civil war and the spillover violence in neighboring Iraq, where the Islamic State militant group (Isis) has launched a war of conquest.

A senior administration official, speaking to the Guardian on condition of anonymity, said that the estimate of roughly 100 represented all Americans who have travelled to Syria or attempted to travel to Syria over the past 18 months, a qualification that US government spokespeople have typically not provided.

Not all of the 20 to 30 Americans went to Syria to join Isis. Some fight with rebel groups resisting the regime of dictator Bashar al-Assad or rival jihadist groups. One such fighter was a 22-year old man from Florida who in May became a suicide bomber for the Nusra Front, al-Qaida’s Syrian affiliate. At least some Americans in the past have fought alongside Assad’s forces, the official said. The Pentagon estimated earlier this month that about 12 Americans fight with Isis.

Nor have all the 100-odd Americans who have travelled or attempted to travel to Syria in the past year and a half gone to fight. The estimate also includes humanitarian aid workers and others attempting to alleviate the Middle East’s most brutal conflict, the official said.

Earlier this month, Jeh Johnson, the US secretary of homeland security, said there was “no credible information that [Isis] is planning to attack the homeland”. The senior US official echoed that assessment, even as the US has launched a war to roll back the advances of Isis in Iraq and will soon conduct airstrikes against it in Syria. Nor did the official see an imminent threat to the US from al-Qaida’s Syrian affiliate, despite recent warnings about its so-called “Khorasan” cell targeting the US domestically.

Echoing several other recent official assessments, the official said that al-Qaida in Yemen poses the greatest danger to the US at home of any jihadist group.

Those westerners who join Syrian militant groups pose a greater threat of terrorist exfiltration to Europe, and particularly to Britain, whose security apparatus has scrambled to identify the British-accented masked jihadist shown on video executing US journalists James Foley and Steven Sotloff. But the official asserted Isis ultimately poses “huge risk” to the US if left unchecked.

“There’s no real indication of either actual planning or capacity to launch such an attack into the US,” the senior official said, although Isis and other groups have “the capability to launch into Britain or into Europe” or Australia, where authorities earlier this month claimed to have uncovered an Isis beheading plot.

Unlike al-Qaida’s central core operation in Pakistan or its Yemen affiliate, neither Isis nor Nusra’s potential threat to the US at home centers around detonating an airliner, the US believes. The senior official said any assault Isis or al-Qaida’s preferred Syrian branch may pose domestically is likely to look more like a “lone wolf” – in which a single individual attempts a terrorist attack, potentially without actual connection to an existing terror group – or a “Westgate Mall”-type assault, a reference to the September 2013 takeover of a major Nairobi shopping mall by al-Shabaab gunmen that killed at least 67 people.

The official would not definitively rule out a threat from Isis or another Syrian jihadist group to US civilian aviation, but considered “some idiot with a gun” the likelier path through which anyone holding a US passport might attempt to bring jihadist experience acquired in Syria into this country. That threat, not seen as imminent now, may increase as the US intensifies its war on Isis, the official acknowledged.

While the US and its European allies focus on westerners joining Syrian jihadists, al-Qaida appears to be providing the Nusra Front with its own foreign fighters: Pakistanis, the official said, who arrive to fight and train others for what has emerged as perhaps the world’s premiere jihadist battlefield. Many of them have coalesced into a group known as Khorasan, believed to be a cell within al-Qaida’s Syrian affiliate focused on attacks on the west.

The US intends this week to mark an escalation point in its campaign against Isis. President Barack Obama plans to chair a Wednesday meeting of the United Nations Security Council concerning Isis, an opportunity the White House wishes to use to galvanize global support for its latest war.

Ahead of the meeting, Secretary of State John Kerry met on Monday at the Waldorf-Astoria with his UK counterpart, Philip Hammond, concerning their “continuing efforts to organize the coalition and plan the road ahead” against Isis, Kerry said. Kerry is also scheduled to meet on Monday with the foreign minister of Saudi Arabia, a regional power that has agreed to host a new US initiative to train and arm Syrian fighters into a proxy ground force.