Russia has received an advance payment from Turkey for S-400 surface-to-air missile systems which Ankara is buying from Moscow, Russian presidential aide for military and technical cooperation Vladimir Kozhin said.
He also said that Turkey would like to take delivery of the missile system before 2019.
"The issue is under discussion," TASS cited Kozhin as saying.
On September 12, Turkish President Recep Tayyip Erdogan said that Ankara had signed an agreement with Moscow to purchase S-400 missile systems and had already made an advance payment.
