Turkey is now “evaluating” the purchase of a long-sought US missile defense system, Turkish state news agency Anadolu reported Friday, hours after the arrival of the rival Russian S-400 system.

“We are evaluating the purchase of the US Patriot missile system, and our relevant institutions continue to study the matter intensively,” Turkey’s defense chief Hulusi Akar was quoted as saying, adding that Turkish troops are already being trained on the installation and use of the Russian system, he said.

Washington has for months warned Ankara against purchasing the rival system, with Congress warning that the decision would trigger sanctions, halt an impending F-35 delivery, and end Turkey’s role in the manufacturing process of the aircraft.

“The radar system would provide Russia with military sensitive info on the F-35, which is our top-quality fifth-generation aircraft,” Andrew Winternitz, acting deputy assistant secretary of defense for European and NATO policy, was quoted as saying. “From our perspective, there are no measures that can mitigate our concerns on this,” he added.

A Pentagon spokesman in May said the US Department of Defense was already working to identify alternative vendors to produce F-35 components manufactured in Turkey, should the S-400 deal go through. Currently, eight Turkish companies are part of the supply chain of American defense contractors Lockheed Martin and Pratt & Whitney to make parts for the F-35. Izmir-based Fokker Elmo, for example, manufactures 40% of the wiring and interconnection system.

They are set to lose $12 billion in contracts should Turkey be removed from the F-35 program. In comparison, Turkey has paid $2.5 billion for the S-400 system, which NATO has emphasized is not compatible with the equipment of the alliance.

A military necessity

Turkey’s defense minister has insisted the decision to purchase the S-400 in 2017 after failed negotiations over the Raytheon-manufactured Patriot system was “not a choice but a necessity,” given ballistic missile threats in the region.

The US, Germany, and the Netherlands, which previously deployed the Patriot system in eastern Turkey, all pulled out their systems in 2015 despite the raging civil war next door in Syria. The move came after Russia began providing air support to the Syrian military against Turkish-backed rebel groups, driving up the risk of a NATO-Russia confrontation.

Ankara declined to buy the Patriot in previous years because the US reportedly refused to allow the transfer of the system’s missile technology in advance of the purchase.

A video published Friday by Anadolu gave the Turkish state explanation as to why it chose the S-400: “What happened during the S-400 purchase? The United States did not give a response to Turkey’s demand for Patriot missiles. Turkey waited for 17 months. NATO allies did not show any support either. And soon Russia made an attractive offer.”

Trump offers solutions

US President Trump appeared to absorb the Turkish line after his meeting with his counterpart Recep Tayyip Erdogan at the G-20 in Tokyo last month, putting full blame on the Obama administration for blocking previous potential deals.

“We have a complicated situation, because the president was not allowed to buy the Patriot missiles,” Trump said. “So he buys the other missile and then, all of a sudden, they say, ‘Well, you can now buy our missile.’ You can’t do business that way.”

The debacle comes at a time of economic crisis for Turkey, whose currency lost more than 50% of its value over the past two years.

But Erdogan appeared confident at the G20 that he had the sympathies of Trump, who said his administration would look at options to avoid the S-400 purchase becoming an issue.

According to US Treasury regulations, passed under Obama, the White House must impose at least five out of 12 available sanctions against any party engaging in a “significant transaction” with the defense sector of the Russian government. The sanctions on offer include restrictions on financial transactions, trade, and even travel by corporate officers.

Trump, if he so chooses, could waive these sanctions if he decides it is in the vital national security interest of the US. As recently as May, Trump invoked emergency powers to circumvent Congress and green light a series of weapons sales to Saudi Arabia and the United Arab Emirates.