WASHINGTON — After months of threatening quick, severe action against Turkey should it accept the Russian-made S-400 air defense system, the Trump administration has yet to react to the system’s delivery.

A Turkish Defence Ministry statement early July 12 said “the first group of equipment” of the S-400 air defense systems reached the Murted Air Base near Ankara on Thursday evening. The delivery of parts of the system will continue in the coming days and authorities will decide “how it will be used” once the system is made operational, Turkey’s defense industry authority said in a statement.

The Pentagon initially called an 11:15 a.m. press briefing July 12 to discuss the S-400 retaliation. It was then switched to 1:45 p.m., then postponed indefinitely. A defense official told reporters that acting Defense Secretary Mark Esper spoke with his Turkish counterpart for half an hour during the afternoon, but said there will be no readout from the call.

As of 1 p.m. on July 13, there was still no statement issued from the White House or the State Department.

The U.S. and other NATO allies have expressed alarm for several years over the purchase of the S-400, with concerns that plugging the Russian system into the alliance could lead to data leaks and security breaches, including concerns it would allow Russians to gain information about the stealthy F-35 fighter.

Gen. Mark Milley, Trump’s choice to be the next chairman of the Joint Chiefs of Staff, said in written testimony to the Senate Thursday that “my recommendation would be to discontinue the transfer of F-35 aircraft to Turkey and unwind Turkey from the F-35 program if Turkey accepts delivery of the S-400. The S-400 is a Russian system built to shoot down aircraft like the F-35.”

Turkey, a partner in the F-35 program that helped fund the development of the jet, plans to buy 100 F-35As. Its first jet was rolled out in June 2018 in a festive “delivery ceremony,” but although Turkey formally owns its jets, the United States has the power to keep the planes from moving to Turkish soil and intends to keep all four existing Turkish jets from leaving the United States.

The U.S. has already stopped training Turkish pilots on the F-35 and has given Ankara until the end of July to get its personnel out of the U.S.

Though the administration has yet to respond, congressional leaders have been vocal. In a joint statement the afternoon of July 12, the bipartisan leadership of the Senate Armed Forces and Foreign Relations committees said “there must be consequences” for Turkey accepting the S-400.

“We urge President Trump to fully implement sanctions as required by law under the Countering America’s Adversaries Through Sanctions Act,” they said in the statement. “Additionally, while all F-35 material deliveries remain indefinitely suspended, we call on the Department of Defense to proceed with the termination of Turkey’s participation in the F-35 program.”

The House and Senate have passed versions of the 2020 defense policy bill that contain provisions meant to bar Turkey from receiving the F-35 if it accepts delivery of Russia’s S-400 system.

The U.S. actions against Turkey with the F-35 are a bilateral issue, but questions now arise about how the S-400 delivery will impact the relationship between Ankara and NATO.

Jim Townsend, a former deputy assistant secretary of defense for Europe who now works for the Center for a New American Security, noted there are often political disagreements inside NATO. But the potential of the S-400 fight is a different level that “actually undercuts” the alliance military capability, he said.

“This isn’t something you can negotiate around,” Townsend said. “This is a big deal, where action has to be taken. It will confront NATO with a political problem that is pretty unique, in the sense of: What do you do with a NATO ally that has taken actions to weaken the military capability of the alliance? How do you deal with that?”

But while the alliance may be caught in the “frag pattern” of the fight between the U.S. and Turkey, Townsend also sees it as unlikely Turkey would leave the alliance or be pushed out. (Legally, NATO experts say, there is no mechanism to force a state out of the alliance.)

And he sees a potential path forward where Turkey can claim political victory while walking back the S-400 purchase, if the U.S. and other allies will allow it: that Turkey accepts the S-400 deliveries but leaves everything crated up in a warehouse while reopening U.S. negotiations, eventually leading to an agreement with the S-400 never made operational.

“Delivery is starting. It hasn’t ended yet. Once delivery is done, these things will stay in crates until Russian technicians come in to help set it up. Then the Turkish forces need training. So there are a lot of steps for this,” Townsend said. “NATO has to come up with something that helps [Turkish President Recep Tayyip] Erdogan get out of this corner. And the question is: Will NATO be patient, or will they be too mad?”

The Associated Press contributed to this story.

Aaron Mehta was deputy editor and senior Pentagon correspondent for Defense News, covering policy, strategy and acquisition at the highest levels of the Defense Department and its international partners.

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