Turkish defense officials say Ankara and Moscow have signed a deal under which Russia will supply up to two S-400 surface-to-air missile batteries to Turkey.
Turkey's Undersecretariat for Defense Industries (SSM) said late on December 29 that delivery of the initial battery of the air-defense system is planned for the first quarter of 2020.
The deal, reportedly worth about $2.5 billion, has caused concern in the West because Turkey is a member of NATO and the antiaircraft weapon systems cannot be integrated into the alliance’s defenses.
Turkey's move to acquire the S-400s also is regarded in some Western capitals as a snub to NATO amid tensions with Russia over its role in the wars in Syria and eastern Ukraine.
The SSM said the purchase of the second S-400 battery was optional under the agreement and that the systems would be managed and operated "independently" by Turkish personnel, not by Russian advisers.
Sergei Chemezov, head of Russian state conglomerate Rostec, told the newspaper Kommersant in an interview published on December 27 that the deal would consist of four batteries of S-400 missiles.
No explanation was given for the discrepancy in the number of batteries being described as part of the deal.
Chemezov said shipments of the missile systems to Turkey were expected to begin in March 2020.
"They are paying 45 percent of the total contract amount as an advance. Fifty-five percent is Russian credit," Chemezov told Kommersant.
The missiles have a maximum range of 400 kilometers and are capable of reaching targets at a maximum altitude of 30 kilometers. Each missile battery can simultaneously hit 80 different targets with two missiles each.
Negotiations on the S-400 deal were first announced by Turkish President Recep Tayyip Erdogan in September.
Russia and Turkey support opposing sides in the Syrian war, but Erdogan and Russian President Vladimir Putin patched up relations that were badly damaged when Turkish jets shot down a Russian warplane near the Syrian border in November 2015.
On December 27, Russian Deputy Prime Minister Dmitry Rogozin said Moscow also expects to sign a deal with India soon on the delivery of S-400s.
Russian officials have also said that Russia and U.S. ally Saudi Arabia are close to signing a deal on supplying the S-400 systems to Riyadh.