While the world has focused on a U.S.-led air assault on Islamic State strongholds in Syria, American officials said they also struck a blow there against a little-known cadre of hardened al Qaeda militants that posed a more immediate threat to the West.
The strikes early on Tuesday on what Washington called the Khorasan Group, so shadowy that U.S. officials had barely uttered its name in public, were staged to disrupt a plot against U.S. or European targets that the Pentagon said was "nearing the execution phase."
The U.S. objective may also have been to take out the leader of the cell, Kuwaiti-born Mohsin al-Fadhli, a reputed former member of Osama bin Laden’s inner circle.
Despite Islamist posts on social media mourning Fadhli's death, there was no confirmation that he was among the dozens reported killed in the bombing raids in northwestern Syria.
The strikes followed lengthy surveillance of Khorasan, described by U.S. officials as a "network" of seasoned al Qaeda fighters with battlefield experience mostly in Pakistan and Afghanistan and now working in league with al Qaeda’s Syrian affiliate, the Nusra Front.
The al Qaeda veterans have used the chaos of Syria’s civil war as cover to try to devise new hard-to-detect bombs and recruit foreign militants holding Western passports to return home and eventually carry out attacks, U.S. officials said.
The Islamic State, which also has al Qaeda roots and flourished during Syria's civil war, has pressed a brutal campaign to establish an Islamic caliphate centered in parts of Syria and Iraq, but is not seen by Washington as an immediate threat outside the region.
U.S. officials said the small Khorasan group, on the other hand, has pursued the singular goal of plotting bombings in the United States and Europe.
"These are al Qaeda veterans who have established a safe haven in Syria to develop and plan external attacks, in addition to construct and test improvised explosive devices and to recruit Westerners for external operations," a senior U.S. official said.
Concern about such plots prompted U.S. authorities to order tighter airport screening for flights to the United States in July, the official said. Airlines were asked to give closer scrutiny to passengers' cellphones and shoes, apparently fearing they could be used to conceal explosives.
Air strikes "quite effective"
After Tuesday’s air strikes, the Pentagon said it was still assessing how badly Khorasan had been hit, but a senior U.S. official said the bombing was “quite effective.”
Islamist militants on social media said there were unconfirmed reports that 33-year-old Fadhli had been killed and they were mourning him. But the U.S. official said, "We don't have confirmation on that leadership target."
Fadhli, according to a 2012 State Department notice that offered a $7 million reward for information on his whereabouts, was an al Qaeda financier close to bin Laden and among the few who knew in advance about the Sept. 11, 2001, attacks.
Still, U.S. officials have offered few details about the group except to say it was planning an "imminent attack." They declined to provide details about the timing.
Its very existence was only acknowledged publicly on Thursday when U.S. Director of National Intelligence James Clapper told an intelligence conference that Khorasan may pose as great a threat to the United States as Islamic State.
Some Islamists contacted by Reuters in Syria did not seem to consider Khorasan a separate group, regarding its members as part of Nusra, one of the major forces fighting to overthrow Syrian President Bashar al-Assad.
Khorasan is the Islamic term for an area including parts of Pakistan and Afghanistan, where al Qaeda’s main council is believed to be in hiding.
"We are not sure what group they are talking about,” one Islamist source in Syria told Reuters. “They are probably making a distinction between Khorasan leaders and others, but this is only a Western term. For us this is all empty words.”
The Syrian Observatory for Human Rights, which monitors the war in Syria, said at least 50 fighters and eight civilians were killed in strikes in northern Aleppo and Idlib provinces on Tuesday.
U.S. officials said those attacks had targeted Khorasan, but Syrian sources said the strikes hit Nusra sites. The Observatory said most of the Nusra fighters killed were not Syrians.
U.S. officials insisted that while Khorasan has worked with Nusra on some activities, the smaller group is tied into the main al Qaeda network, which is run by Ayman al-Zawahiri, bin Laden’s successor, and is not pursuing the fight against Assad.
“The Khorasan Group includes ... core al Qaeda operatives from Afghanistan and Pakistan who made their way to Syria," Ben Rhodes, Obama’s deputy national security adviser, told reporters.
"And we have been monitoring over the course of many months the development of plotting against the United States or Western targets emanating from Syria," he said.