American officials are worried al-Qaeda is planning a possible attack next week to coincide with the one-year anniversary of the death of Osama Bin Laden.

FBI and the U.S. Department of Homeland Security issued a four-page bulletin to American law enforcement early Thursday morning regarding the anniversary of the raid on the Pakistani compound where Bin Laden was hiding.

They also warned of al-Qaeda’s renewed attempt to target western aviation and the possibility of a so-called “Lone Wolf Attack.”

Officials in the U.S. said there will be extra vigilance at airports, transportation hubs and American military facilities over the next week.