Nov. 10 (UPI) -- The U.S. Department of Homeland Security has updated a terror bulletin to warn about potential attacks using drones and explosives in air cargo.
The bulletin, revised Thursday, is an advisory below the level of an "Elevated Alert" or an "Imminent Alert."
"Some terrorist groups overseas are using battlefield experiences to pursue new technologies and tactics, such as unmanned aerial systems and chemical agents that could be used outside the conflict zones," it read. "Additionally, terrorists continue to target commercial aviation and air cargo, including with concealed explosives."
The warning also mentions that terrorist organizations urge recruits to rely on "easy-to-use tools" like vehicles, knives, homemade explosives and poison.
"Terrorists continue to target commercial aviation and air cargo, including with concealed explosives."
ABC News reported that a senior DHS official identified an "uptick in terrorist interest" in using unmanned drones as weapons has been noticed.
The department said it has installed new security measures in airports overseas, with cooperation from airlines that fly to the United States. In June, the agency announced "enhanced screening" of passengers and electronic devices, as well as noticeable and undetected security at airports.
Terrorists still regard "aviation as the crown jewel target," White House chief of staff John Kelly, the former DHS chief, said this summer.