“We can say that that Sinai plane crash was a terror act,” Bortnikov told Putin. According to the FSB chief, experts analyzed passengers’ belongings as well as the parts of the plane. “After the examination on all these objects, we have found traces of a foreign-made explosive substance,” Bortnikov said.

“During the flight, a homemade device with the power of 1.5 kg of TNT was detonated. As a result, the plane fell apart in the air, which can be explained by the huge scattering of the fuselage parts of the plane,” he added.

Vladimir Putin has vowed to find and punish the culprits behind the Sinai plane attack. “Our military work in Syria must not only continue. It must be strengthened in such a way so that the terrorists will understand that retribution is inevitable,” he said.

The Federal Security Service director also announced a reward of US$50 million for information on those behind the terror attack on the A321.

The Kogalymavia A321 air crash took place over the Sinai Peninsula in Egypt on 31 October. All 224 people on board the plane were killed, making it the deadliest air accident in modern Russian aviation history.