House and Senate leaders of the armed services and foreign relations committees on July 12 urged swift action to counter Turkey’s acquisition of a Russian-made weapon system that the Defense Department has long said is incompatible with the NATO-operated F-35 Joint Strike Fighter.

After months of stating its intent to procure the S-400 anti-aircraft weapon system, Ankara has taken ownership of the system, The Associated Press reported Friday morning. The Pentagon has long said that should Turkey move ahead with the purchase of the S-400, the United States would remove the NATO member state from the F-35 program, of which it is a development partner.

An F-35 Lightning II streaks across the sky while doing maneuvers to the Eglin Air Force Base runway. The 33rd Fighter Wing-owned aircraft is a fifth-generation fighter and used to train pilots and maintainers. (U.S. Air Force photo/Samuel King Jr.)

Acting Secretary of Defense Mark Esper said in a Friday statement that the department is “aware of Turkey taking delivery of the S-400” and “our position regarding the F-35 has not changed and I will speak with my Turkish counterpart Minister Akar this afternoon.”

“So there will be more to follow after that conversation,” the statement ended.

A Defense Department official told reporters Friday afternoon that Esper spoke with Turkish Defense Minister Huluci Friday afternoon for 30 minutes. No statement or readout was provided. An on-camera press briefing at the Pentagon on the subject that was originally scheduled for Friday morning has been indefinitely rescheduled.

The leaders of the Senate Armed Services Committee and Senate Foreign Relations Committee issued a joint statement Friday afternoon, stating, “By accepting delivery of the S-400 from Russia, President Erdogan has chosen a perilous partnership with Putin at the expense of Turkey’s security, economic prosperity and the integrity of the NATO alliance.”

The members – which include SASC Chairman Jim Inhofe (R-Okla.) and Ranking Member Jack Reed (D-R.I.), as well as SFRC Chairman Jim Risch (R-Idaho) and Ranking Member Robert Menendez (D-N.J.) – urged President Trump to implement sanctions as laid out in the Countering America’s Adversaries Through Sanctions Act, and called on the Pentagon “to proceed with the termination of Turkey’s participation in the F-35 program.”

Former Acting Defense Secretary Patrick Shanahan sent a letter to Turkish officials in June laying out steps to remove Turkey from the F-35 program by July should the S-400 purchase move forward (Defense Daily, June 7). The Pentagon ceased the delivery of materiel related to the F-35 program to Turkey in April and said it was beginning to look into alternative suppliers for Turkish-made parts. Lockheed Martin [LMT] is the prime contractor for the Joint Strike Fighter.

Lawmakers and the Defense Department had been working to convince Turkey to procure the Raytheon [RTN]-built Patriot air defense system instead of the S-400. “Unfortunately, President Erdogan rejected multiple attempts by the United States to preserve our strategic relationship while enabling Turkey to defend its airspace with F-35 aircraft and the Patriot air defense system,” the Senate committee leaders said.

House Foreign Affairs Committee Chairman Eliot Engel (D-N.Y.) and Ranking Member Michael McCaul (R-Texas) issued a joint statement Friday afternoon, echoing their Senate colleagues’ call for the U.S. government to end Turkey’s participation in the F-35 program, “and to sanction Turkish individuals doing business with the Russian defense sector, as required by law.”

“Turkey and Erdogan must face stiff consequences for this decision,” they said.

The Pentagon’s Under Secretary for Acquisition and Sustainment, Ellen Lord, told reporters in May that the department was working to minimize any potential delays to the F-35 program that could come from Turkey being ousted as a partner (Defense Daily, May 10).

House and Senate lawmakers each introduced bills in the past few months that would prevent Turkey from receiving the F-35 should they move forward with procuring the S-400 .

House Armed Services Committee (HASC) Chairman Adam Smith (D-Wash.) told reporters Friday that he continues to support the administration’s decision to revoke the F-35 from Turkey in the wake of the S-400 deliveries.

“I don’t imagine that [decision] will change … but I think we should work closely with the administration on this to make sure we have the right response,” he said.