No US airlines regularly service Sharm el-Sheikh, and the US' Federal Aviation Administration (FAA) issued a flight advisory in March 2015 for the Egyptian peninsula, warning aircraft not to fly below 26,000 feet (7,900 meters) over Sinai because of the possibility of "anti-aircraft and shoulder-fired, man-portable air defense systems" and extremist activity.
"I'm not aware of any plans to update that specific advisory," White House spokesperson Josh Earnest told reporters.
"We have become concerned that the plane may well have been brought down by an explosive device," reads a statement issued by the office of Prime Minister David Cameron.
Metrojet flight 9268, a Russian Kogalymavia Airbus A-321 passenger airliner, with 217 passengers and seven crew members on board, crashed in the Sinai Peninsula in Egypt on Saturday leaving no survivors. An official cause for the crash has not been determined, though the tragedy has prompted rampant speculation with theories ranging from mechanical error to terrorist sabotage.