The comments came after a second shipment of equipment needed to make the S-400s operational was delivered to Turkey on Saturday.
Turkey’s purchase of the Russian S-400 missile system was “not a choice but a necessity” because it is under serious threat, its defence minister told the United States.
The US has strongly urged Turkey to pull back from the deal – the first such move between a NATO member and Russia – warning Ankara it will face economic sanctions, reportedly costing more than $2bn.
Defence Minister Hulusi Akar told his American counterpart Mark Esper by phone on Friday buying the controversial defence system does not mean a change in the country’s strategic orientation.
Turkey was under “serious threat” and its acquisition of S-400s was necessary, Akar said, adding it was obliged to take measures against “intensive attacks” from the Syrian border as it is a priority.
The first equipment for the advanced air-defence system was delivered to the Murted airbase outside the capital on Friday, the defence ministry said, adding deliveries would continue in the coming days.
“Delivery of S-400 Long Range Air and Missile Defence Systems resumed today,” a defence ministry statement said on Saturday. “The fourth Russian plane carrying S-400 parts landed at Murted Airport outside Ankara.”
The US was publicly silent on how it would respond to the Russian delivery.
Washington fears if Ankara integrates the S-400s into its defences, data about the US-built F-35 fighter jet could leak back to the Russians.
Akar told Esper that Turkey was still assessing a bid to acquire the US Patriot air-defence system, and a deterioration of bilateral relations would not serve the interests of either country.
US officials urged Turkey to buy Patriot missiles rather than the S-400s from Moscow.
But Ankara said it was the United States that refused to sell Patriots to Turkey, and that led it to seek other vendors. Russia offered a better deal, including technology transfers, it added.
The US has said Turkey will not be allowed to participate in the programme to produce hi-tech F-35 stealth fighter jets or buy them. Washington has repeatedly said the Russian missiles are incompatible with NATO systems and a threat to the F-35s.
“In military terms, it is an advantage of the US to have access to the Russian systems within the NATO armoury to understand the way the system works and deploy countermeasures against it,” he added.
Mustafa Adyin, from Turkey’s Kadir Has University, noted that Turkey has said it is “totally free” to use the defence system as it sees fit, but it is unclear what restrictions Moscow has imposed in the deal.
“We don’t know exactly the extent that the Russians would allow these missiles to be used and what kind of targeting possibilities… Much depends on the coding and friend-or-foe identifications,” he said.
NATO, which counts Turkey as one of its members, is also “concerned about the potential consequences” of the S-400 purchase, an official told AFP news agency.
Members of the US Congress have repeatedly voiced opposition to the move and threatened sanctions.
“President Erdogan was given a very clear choice. Unfortunately, he has clearly made the wrong one,” said Eliot Engel and Michael McFaul, the top Democrat and Republican, respectively, on the House Foreign Affairs Committee.
Fitch downgrades Turkey’s rating
Sanctions would mark a new low in the already-tense relations between Turkey and the US. Last year, the US imposed sanctions on Turkey over its detention of an American pastor, triggering a Turkish currency crisis. The sanctions were later lifted upon the pastor’s release.
Fitch Ratings downgraded Turkey’s sovereign rating to “BB-” on Friday and said it remained vulnerable to deterioration of ties with the US.
Turkey’s S-400 deal with Russia has also raised concerns in Western circles that Turkey is drifting closer to Moscow’s sphere of influence.
Ankara has refused to bow to pressure from Washington, insisting that choosing which defence equipment to buy is a matter of national sovereignty.