The date for the purchase of more S-400 missile defense systems from Russia is only a technical matter, and an agreement will be made soon, a Russian presidential official was quoted as saying on Monday.
The head of Rosoboronexport, a Russian arms export company, said last month that Moscow hoped to conclude an agreement to supply Turkey with more S400 systems in the first half of next year.
Such a move would further strain relations between Turkey and the United States, which suspended Ankara's participation in the F-35 fighter jet program, once a buyer and producer country, as punishment for buying the S400 earlier this year.
"The timing of buying a second set of S400 systems is only a technical matter, I think it will be soon," RIA news agency quoted an official in Turkey's security and foreign affairs as saying.
On November 26, Rosoboronexport chairman Alexander Mikhayev told the Russian news agency that Russia and Turkey were seriously considering using Ankara as an optional clause in the original contract, to receive more S400 systems, and that talks were focused on financial matters.