Russia has sold its advanced S-400 air defence missile system to Turkey for over $2 billion, Sergei Chemezov, the head of state conglomerate Rostec, said on Thursday, the TASS news agency reported.
The deal with Turkey, a NATO member, has caused some disquiet in the United States.
Turkey originally awarded a $3.4 billion contract for a defence system to China in 2013, but cancelled that two years later, saying it would concentrate on developing a system domestically.