Al Nusra Front
A fighter from the Islamist Syrian rebel group Al Nusra Front is seen in front of a burning vehicle, caused by what activists said were missiles fired by a Syrian Air Force fighter jet, at their base in Raqqa province, eastern Syria, May 12, 2013. Reuters

In September the U.S. dropped cruise missiles on a cell of al Qaeda militants in Syria known as the Khorasan group. Senior officials said the strikes on a facility near Aleppo were justified because the group was thought to be planning an imminent attack on the West. But since that announcement, the Khorasan group has disappeared from the conversation, suggesting that it has either folded into its partner organization, Al Nusra, also an al Qaeda offshoot, or it does not pose a serious, imminent threat to the West.

In his speech Sept. 23 after launching airstrikes in Iraq and Syria, President Barack Obama said the Khorasan members were “seasoned al Qaeda operatives in Syria.” “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,” he said. “This is a core principle of my presidency: If you threaten America, you will find no safe haven.”

The U.S. claimed to have killed two leaders of the group who were planning imminent attacks on the West. “We believe that the individuals that were plotting and planning it have been eliminated,” Rear Adm. John Kirby, a Pentagon spokesman, said the morning after the strikes on Khorasan.

Other senior U.S. officials later admitted that it was still not clear whether those two leaders had been killed and it was still a possibility the group was planning attacks. A senior Defense Department official told Foreign Policy magazine that “an assessment of the strikes yielded no conclusive evidence that the Khorasan group’s leader and his followers were killed.” FBI Director James Comey told CBS's “60 Minutes” that the group might still be looking to attack the U.S. “very, very soon.”

There are clues that point to the possibility of Khorasan joining forces with Al Nusra, another al Qaeda offshoot in Syria. International Business Times reported in September that United Nations documents reveal that Khorasan's leader has deep, previously established connections to Al Nusra leaders.

Muhsin al-Fadhli, the alleged leader of Khorasan, was arrested in Kuwait in 2003 and then released; he went on to a remarkable career in the top echelons of al Qaeda. Some of the al Qaeda leaders he has been linked to have also been arrested by other Middle Eastern governments but subsequently released, according to U.N. documents. Fadhli may have been killed in the U.S. airstrikes on Syria this week; reports have differed.

The man whose full name appears in U.N. documents as Muhsin Fadhil Ayed Ashour al-Fadhli arrived in Syria last year.

Intelligence agencies have known of Fadhli and his link to Osama bin Laden as far back as 2005, and possibly before. In fact, the United Nations listed his exact address in documents published by the U.N. Al Qaeda Sanctions Committee, which works closely with Interpol, an international police organization. Several al Qaeda militants linked to Fadhli were added to a sanctions list when the Al Qaeda Sanctions Committee met Aug. 14 of this year.

The U.N. added Abdul Mohsen Abdallah Ibrahim al Charekh to the sanctions list on Aug. 15 for being associated with al Qaeda and “participating in the financing, planning, facilitating, preparing or perpetrating of acts or activities by, in conjunction with, under the name of, on behalf of, or in support of” Jabhat al-Nusra -- the al Qaeda offshoot operating in Syria. Charekh used to serve as the “deputy” for Fadhli before he moved to Syria in April 2013 to join Al Nusra.

Given these connections, it is possible the Khorasan group has officially joined forces with Al Nusra, or was always a part of its network of fighters. In recent weeks, Al Nusra has picked up fighters from smaller, splinter Islamist battalions. It is said to be gaining momentum in Syria, given its new supporters. And it has made territorial gains in both Idlib and Aleppo in northern Syria.

Al Nusra launched a series of operations this month in what the Washington Post called a “concerted push to vanquish the moderate Free Syrian Army.” This caused significant territorial and weapons loss for moderate rebels, grouped under the FSA label, in Idlib province, an opposition stronghold. Following Al Nusra’s attacks in Idlib on moderate rebel groups, Harakat Hazm, one of the biggest receivers of U.S. weapons, signed a truce with the al Qaeda offshoot, but that truce did not hold.

The other possible scenario for the recent lack of focus on the Khorasan group is that it is no longer, or was never, an imminent threat to the West. Currently more U.S. attention and military resources are being put into fighting the Islamic State group, also known as ISIS or ISIL. Repelling ISIS in places such as Kobani, Syria, and Erbil, Iraq, seem to be a bigger urgency for the U.S. than the Khorasan group, which officials said previously was planning to attack the U.S. homeland.

Since the attacks on Khorasan in September, U.S. officials have dodged questions about whether the group has lost momentum or if it is still active in Syria. A retired director of the National Counterterrorism Center, Matthew Olsen, told CNN that Khorasan "is still in the same place as it was before."