The United States suspended Turkey’s delivery of F-35s in an effort to push Ankara to stop getting the Russian S-400 anti-missile system

The United States said on Monday it would suspend delivery of its F-35 fighter jets to Turkey as well as work with them on the aircraft program after its NATO ally insisted on a major arms purchase from Russia.

After months of warnings, the United States confirmed that Turkey’s decision to buy the Russian S-400 missile system was not compatible with Turkey’s continued involvement in the F-35 program.

“Pending an explicit decision by Turkey to refrain from receiving the S-400, deliveries and activities related to the operationalization of the F-35s in Turkey have been suspended,” said Pentagon spokesman Charles Summers Jr..

“If Turkey buys the S-400 system, it would put the F-35 at risk”, he said in a statement.

US officials have expressed concern that Turkey’s military dealings with the two sides could enable Russia to obtain F-35-related information that could prompt it to develop the S-400 accuracy against Western aircraft.

The Pentagon said it had begun looking for second sources to produce F-35s currently being developed in Turkey.

“We deeply regret the current situation in our F-35 partnership with Turkey, but the Defense Department is taking precautionary measures to protect joint investments in sensitive technology”, Summers said.

Turkey has planned to buy 100 F-35A fighters and its pilots have already begun training in the United States.

The manufacturer of these aircraft, “Lockheed Martin” it expects that the value of contracts with Turkish companies to manufacture pieces of F-35 fighter jets to 12 billion dollars.

The eight Turkish companies involved in the deal include company, which makes a panoramic display of the F-35 cockpit and another company which make up to 40 percent of the wiring and interconnect system, according to Lockheed Martin.

Buying a Russian system is very rare for a NATO member country, the Western alliance that was formed to confront the Soviet Union.

The announcement came two days before the foreign ministers of the 29 NATO member states met in Washington to mark the 70th anniversary of the coalition, hours after the party of Turkish President Recep Tayyip Erdogan “Justice and Development” for a sudden setback in the municipal elections in Ankara and Istanbul.

Erdogan, whose relations with the West have worsened dramatically at a time when he is cracking down on opponents at home, is increasingly looking to Moscow as a partner.

Turkey has become the favorite destination for Russian tourists, an important support for the country’s economy.

Russian Foreign Minister Sergey Lavrov visited Turkey last week, where his counterpart, Zhaoshoglu, insisted that the purchase of the S-400 would go ahead.

“We’ve an agreement with Russia and we are committed to it,” Zhaoshoglu told reporters.

In the hope of providing an alternative, the United States agreed last year to sell Patriot missiles to Turkey.

Four members of the Senate last week proposed blocking the delivery of F-35s to Turkey if they purchased the S-400.

Democratic Senator Chris van Hollen praised the Pentagon’s decision to suspend delivery of US fighter jets to Ankara.

Relations between Turkey and the United States deteriorated last year when US President Donald Trump imposed additional customs duties that brought down the Turkish lira against the backdrop of the trial of US pastor Andrew Branson.

Branson was released and Trump’s relationship with his Turkish counterpart apparently improved before he spoke to him before his sudden decision to withdraw his troops from Syria.

But tensions quickly returned to the forefront as the United States worried that Turks could attack Kurdish allies allied with Washington in Syria and try the US consulate officer in Istanbul, Metin Topuz, on espionage charges.

Tobuz is a Turkish citizen accused of being linked to Islamic preacher Fathullah Gulen, who lives in the United States.

Erdogan has repeatedly asked the United States to extradite Gulen, whom the Turkish president accuses of masterminding the failed coup in 2016.