From the BBC story:

ABC News in America has reported that US law enforcement officials received warnings two weeks ago of terror attacks in Glasgow and Prague, the Czech Republic, against "airport infrastructure and aircraft".

Brian Ross, head of ABC News' Investigative Unit, claimed the warnings apparently never reached officials in Scotland, who said this weekend they had received "no advance intelligence" that Glasgow might be a target.

Mr Ross said he had been told by American officials that the intelligence reports led to the assignment of Federal Air Marshals to flights into and out of both Glasgow and Prague.