A real-size mock of an F-35 fighter jet is displayed at the Japan International Aerospace Exhibition in Tokyo, Nov. 28, 2018. Photo: Reuters / Tim Kelly.

The United States cannot unilaterally remove Turkey from the F-35 fighter jet program as the partnership agreement does not allow it, Turkey’s head of Defense Industries Directorate said on Friday.

“No single country can say they don’t want you and then remove you from the program,” Ismail Demir told reporters.

“This isn’t part of the agreement, this isn’t something you can just say ‘I exclude you’ about. The F-35 project is a partnership and nowhere in the agreement does it allow a unilateral removal of one country,” he said.

Ankara and Washington have been at loggerheads for months over Turkey’s planned purchase of Russian S-400 missile defense system. The United States says the S-400s are incompatible with NATO’s defense network and could compromise its F-35 fighter jets, an aircraft Turkey is helping build and planning to buy.

In a letter to Turkey, the Pentagon has warned Ankara will be pulled out of the F-35 program unless it changes course. Washington has already stopped accepting more Turkish pilots for training in the US and halted delivery of equipment related to the program.

The United States says Turkey’s S-400 acquisition poses a threat to Lockheed Martin Corp’s F-35s. It has threatened to impose sanctions on Ankara under its Countering America’s Adversaries Through Sanctions Act (CAATSA), the possibility of which has spooked investors and helped cause a selloff in the lira this year.

Demir said such sanctions could have a brief impact on Turkey’s defense industry. “Our defense industry produces parts for the F-35, so in the event of sanctions being imposed, our industry would experience a rough patch, but we’ll then get passed this,” he said.