On Sunday the US announced it had killed the "highest-ranking leader," Sanafi al-Nasr, of an elite al-Qaeda group known as the Khorasan Group. Not much has been said about the entity, maybe because there's no real confirmation it exists.
The Khorasan Group is an organization of veteran al-Qaeda militants based in Syria, according to the US, based in Syria to train foreign fighters to conduct attacks in their home countries.
Everything we know about the group has come from US officials. News of the Khorasan Group first appeared in an Associated Press report on Sept. 13, 2014, three days after the US announced it would begin conducting airstrikes against Daesh. The group concerned the Defense Department more than Daesh (ISIS), the report said.
1/4 Very good piece by @KenDilanianAP and @esullivanap here dealing with "Khorasan group" dispatched to Syria by AQ: http://t.co/ICsv0O8vzZ
— Thomas Joscelyn (@thomasjoscelyn) September 13, 2014This is what the Google trend for Khorasan Group looks like:

Remarkably, though, US airstrikes seem to be incredibly effective on this elite, secret group. The Pentagon said it's killed five of its leaders in the past four months alone. And with all of the success surrounding this group, some began to think it was a US effort to bolster support for its involvement in Syria.
The Intercept in May quoted the head of al-Nusra Front himself, Abu Muhammad al-Jolani, saying the group didn't exist:
The so-called Khorasan Group, supposedly active within our ranks, doesn’t exist. We first heard about it via the media after the US-led coalition bombed us. It is merely a Western invention to justify the bombings on us. There are some brothers from Khorasan who joined our strife though.
Then there are Syrian activists on the ground who also said the name was new to them.
Syrian activists telling us theyve never heard of Khorasan or its leader
— Richard Engel (@RichardEngel) September 24, 2014Maybe it's true. Maybe there is in fact a group of veteran al-Qaeda members planning attacks against the Western world, more dangerous than established groups taking swaths of territory like Daesh or Nusra.
But there are some critical questions to ask before taking the US government for its word.
By Hayat Norimine