Russia has sent missile systems to Syria to protect its military forces there, the head of Russia's air force said on Thursday.
Colonel General Viktor Bondarev said fighter jets could be hijacked in countries neighbouring Syria and used to attack Russian forces.
"We have calculated all possible threats. We have sent not only fighter jets, bombers and helicopters, but also missile systems," Bondarev told Komsomolskaya Pravda newspaper.
"We must be ready."
