If it wanted to take down Western passenger aircraft, al-Qaeda needed recruits with Western passports, and Syria was the place to find them. US President Barack Obama's doctrine has called for unilateral strikes on direct threats to the US. Credit:AFP Pentagon spokesman Admiral John Kirby said in a briefing on Tuesday that Khorasan had used Syria, "to plan external attacks, construct and test improvised explosive devices and recruit Westerners to conduct operations". Director for Operations, Lieutenant General William Mayville, expanded on this, saying, "We've been watching this group closely for some time, and we believe the Khorasan group was nearing the execution phase of an attack either in Europe, or the homeland". "We know that the Khorasan group has attempted to recruit Westerners to serve as operatives or to infiltrate back into their homelands.

"The Khorasan group is clearly not focused on either the Assad regime or the Syrian people. They are establishing roots in Syria in order to advance attacks against the West and the homeland." Director of National Intelligence James Clapper mentioned the group in testimony. Credit:AP Since then, CNN reported that officials had told them Khorasan had constructed devices that may avoid airport detection, including clothes dipped in explosive material. In the wake of the strikes the US Department of Homeland Security has issued a bulletin warning law enforcement agencies to be on heightened alert for lone-wolf terror attacks in the US.

Now that the attacks against Khorasan have been launched it is easy to look back over the official record to find hints of the administration's concerns, if only for its resounding silence on the group. Time and again as administration officials made the case for strikes against Islamic State militants they warned that while the Islamic State (also known as ISIL or ISIS) posed a threat to American interests in the region, only al-Qaeda had organisational capacity and the will to attack the West. In early September the National Counterterrorism Centre Director Matthew Olsen said at a Brookings Institution event that while IS posed a threat in the region, "We have no credible information that ISIL is planning to attack the United States". A little over a fortnight later Mr Olsen, whose agency is responsible for setting the terrorism threat level, told a Congressional hearing, "In Syria we've seen veteran al-Qaeda fighters travel from Pakistan to take advantage of the permissive environment there". "Al-Qaeda's official branches in Yemen and Somalia continue to remain extremely active. Of course over the past five years, al-Qaeda in the Arabian Peninsula sought on three times to take down an airplane bound for the United States."

Not once did he mention Khorasan by name, although asked by a reporter later he confirmed that was the group he was referring to. The following day as passengers on many flights bound for the US found themselves subjected to increased screening, White House spokesman Josh Earnest was asked by a reporter during the daily briefing whether the President had been briefed on an al-Qaeda-linked group called Khorasan, and whether it might pose more of a threat than IS. "I'm limited in what I can say. But what I can tell you is that our intelligence professionals have long spoken about the host of terror threats that are emanating from Syria," he replied, not repeating the name Khorasan. "You've also heard me discuss quite a bit about the challenges posed by foreign terrorist fighters. And next week you will hear directly from the President when he chairs a UN Security Council session on this very topic." ABC News notes that it can find no record of any White House official mentioning Khorasan in any briefings on Syria.

Director of National Intelligence James Clapper let the name slip once during a conference on security last week, but even that was during a Q and A session - prepared remarks did not mention the group. President Obama himself did not utter the word Khorasan publicly until after the cruise missile attack on them he ordered had already been carried out. Leaving the White House for the UN meeting in New York he paused and made an address. The first part of his short speech detailed the coalition of nations who had attacked IS targets, but then he turned to the strikes on the Khorasan. "Last night, we also took strikes to disrupt plotting against the United States and our allies by seasoned al-Qaeda operatives in Syria who are known as the Khorasan group," he said. "And once again, it must be clear to anyone who would plot against America and try to do Americans harm that we will not tolerate safe havens for terrorists who threaten our people."

Even this language is telling. In June Obama made a speech detailing how he would use American force. It has become known as the West Point speech, the basis of what some call the Obama doctrine. In it Obama said that when threats arise against the international order America would seek to build and lead coalitions to challenge them. But when America is threatened directly it would strike unilaterally. He has maintained this line ever since, even as he prepared the nation for attacks against IS in Iraq and Syria. There were three waves of attacks over Syria on Tuesday night. The second and third were made up of American missiles aircraft and drones and the fighter jets of its regional allies. But the first - that volley of Tomahawk cruise missiles launched against the Khorasan - was an entirely American effort.