If ISIS really did bring down a Russian passenger jet in Egypt, it wasn't with a missile, according to American officials. US officials tell CNN and NBC News that an American infrared satellite detected a heat flash in the area at the time of the crash, but not the heat trail of a missile. Analysts say the heat flash could have been caused by a number of things, including a bomb, a fire on the plane, a fuel tank exploding, or even the plane slamming into the ground, although an official tells NBC it appears that the plane "disintegrated at a very high altitude," as Russian authorities have said. The airline says it has determined that "external activity" is the only thing that could have caused the crash of Flight 9268.
The airline says the age of the 18-year-old Airbus A321 was not an issue, and a tail strike accident in 2001 didn't cause damage that could have led to the crash, reports the New York Times, which notes that the airline started out as Kogalymavia and now calls itself Metrojet. A French aviation expert tells CBS News that suggestions of "external activity" mean sabotage is another possibility. "Either a bomb was placed during the stopover and programmed to explode after takeoff, or a mechanic sabotaged the plane," he says. "These are the two most probable hypotheses." Egypt's President Abdel-Fattah el-Sissi tells the BBC that the cause is unknown and ISIS' claim to have brought the aircraft down, killing 224 people, is only "propaganda." (Read more plane crash stories.)