WASHINGTON — Turkey faces “grave consequences” if it continues plans to buy the Russian S-400 air defense system, including being blocked from buying the F-35 fighter jet and Patriot air defense systems, the Pentagon’s top spokesman said Friday.

Asked about comments made earlier this week by America’s top general in Europe, acting press secretary Charlie Summers said: “If turkey takes the S-400, there would be grave consequence in terms of our military relationship, and the Patriots and the F-35s.”

“They will not get the F-35s if they take the S-400,” he added, later indicating the potential Patriot sale would also be blocked.

The comments came a few days after U.S. European Command head Gen. Curtis Scaparrotti said it would be his best military advice to bar Turkey from getting the F-35, should the country continue on the path of procuring the S-400.

The comments come as part of this week’s back-and-forth between Ankara and Washington on the issue.

On March 6, Turkish President Recep Tayyip Erdoğan told local television channels that not only will Turkey stick to its S-400 acquisition plans, but it might also seek the more advanced S-500 in the future.

"We signed a deal with Russia for the purchase of S-400, and will start co-production. It’s done,” Erdoğan said, according to local translations. “There can never be a turning back. This would not be ethical, it would be immoral. Nobody should ask us to lick up what we spat. Later, we may work with S-500s.”

And Friday morning, Turkish National Defence Minister Hulusi Akar said the U.S. not handing over F-35s to Turkey would be illegal and expressed his belief a solution could be found.

"Our peers say it is impossible to pass the sale of the F-35 aircraft in Congress, but we are working on a solution,” he said, according to the Turkish Anadolu Agency. “We have to protect and cover our 82 million citizens. S-400 systems will begin to be established in October. The Air Force continues to work where they’ll be stationed.”

Turkey plans to buy 100 Joint Strike Fighters over the course of the program, and its first F-35 pilots have already begun training alongside U.S. pilots at Luke Air Force Base, Arizona. Turkish companies play a key industrial role in the program as one of the producers of the center fuselage and the maker of the cockpit display.

As a result of the planned S-400 procurement, the Pentagon launched a large study into whether it would be possible to remove Turkey from the F-35 industrial base.

Turkey is also seeking the Patriot missile defense system. In December, the U.S. State Department cleared Ankara to buy the system for an estimated $3.5 billion, but discussions are still in the early stages of actual procurement.