The decision has significant implications for the cohesion of NATO, whose central strategic purpose is to defend against Russian aggression. Now that NATO member Turkey has chosen to buy and deploy the Russian-made S-400 air defense, it will no longer be fully part of the alliance's air defenses, which are at the core of NATO strategy.
The U.S. government's concern is that the S-400 could be used to gather data on the capabilities of the F-35, and that the information could end up in Russian hands. Pentagon officials sought to downplay the rift, noting that Turkey has been a key ally for more than six decades.
"The U.S. still values our strategic partnership with Turkey," said Ellen Lord, the Pentagon's chief weapons buyer, who told a news conference that the U.S. has suspended Turkey from the F-35 program and is beginning the process of its formal removal. Lord said Turkey stands to lose $9 billion in future earnings as an F-35 parts supplier.
David Trachtenberg, the deputy undersecretary of defense for policy, told reporters the U.S.-Turkey military partnership "remains very strong," and U.S. and Turkish forces will continue to exercise together. He declined to explain how Turkey can remain a full partner in NATO's integrated air defense while using a weapon system built by NATO's chief adversary.
It's clear, however, that senior U.S. officials worry about the future of the relationship with Turkey. Mark Esper, Trump's nominee to be the next secretary of defense, told his Senate confirmation hearing on Tuesday that it is "very disheartening to see how they have drifted over the past several years" away from the West.
Although it is never publicly acknowledged by the U.S. government, the Pentagon stores nuclear weapons at Turkey's Incirlik air base. Some national security experts question the wisdom of continuing that arrangement, given Turkey's drift.
Earlier this week, Turkish President Recep Tayyip Erdogan said his government hopes to co-produce high-tech weaponry systems with Russia in the future, further defying the United States and other NATO allies. Turkey refused to bow to U.S. pressure, saying its Russia deal is a matter of national sovereignty and that the agreement could not be cancelled.
The decision to remove Turkey from the F-35 program had been expected, although administration officials spent months trying to talk the Turks into reversing course. The final straw was Turkey's announcement last weekend that it has begun taking delivery from Russia of components for the air defense system, called the S-400.
"Unfortunately, Turkey's decision to purchase the Russian S-400 air defense systems renders its continued involvement with the F-35 impossible," a White House statement said. "The F-35 cannot coexist with a Russian intelligence collection platform that will be used to learn about its advanced capabilities." That "platform" is the S-400.
The White House did not say explicitly that Turkey will be kicked out of the F-35 program, but the Pentagon did. Lord said the process of fully removing Turkey is under way and should be completed by next March 31. She refused to say whether the decision could be reversed.
Turkey makes more than 900 components for the stealth aircraft, which is sold internationally. Removing it as a supplier means the Pentagon is lining up alternative manufacturers for those parts. Lord said many of those alternatives will be American suppliers, and that the Pentagon is spending between $500 million and $600 million "to shift the supply chain."
Congress appears generally supportive of the administration's moves against Turkey. "America simply cannot send its most advanced military technology to countries where adversaries like Russia will have access to it," said Sen. Tom Cotton, an Arkansas Republican who sits on the Armed Services Committee.
Trump announced on Tuesday that the S-400 purchase means Turkey will not be allowed to purchase any F-35 planes, but he did not address the related questions of Turkey's role in F-35 production or the likelihood that the S-400 purchase from Russia will trigger U.S. sanctions under the Countering America's Adversaries Through Sanctions Act. The State Department this week has been silent on whether those sanctions will be imposed.
The break with Turkey over its purchase of a Russian weapon system is symptomatic of a deeper division between Ankara and its Western allies and partners. Army Secretary Mark Esper, Trump's nominee to become secretary of defense, told his Senate confirmation hearing Tuesday he is troubled by Turkey's decision to defy the United States on the S-400, suggesting that it reveals a broader strategic problem.
"It is very disheartening to see how they have drifted over the past several years," Esper said. Turkey has complained that it was not given favorable terms to buy the American alternative to the Russian S-400 air defense system. The White House, however, said in its statement Wednesday that Turkey had plenty of chances to buy the U.S. Patriot system.
"This administration has made multiple offers to move Turkey to the front of the line to receive the U.S. Patriot air defense system," it said.