An Israeli Air Force F-35 “Adir” fighter jet. Photo: Major Ofer / Israeli Air Force.

A US Senate committee passed its version of a $716 billion defense policy bill on Thursday, including a measure to prevent Turkey from purchasing Lockheed Martin F-35 Joint Strike Fighter jets.

The amendment to the National Defense Authorization Act, or NDAA, from Democratic Senator Jeanne Shaheen and Republican Senator Thom Tillis, would remove Turkey from the F-35 program over its detention of US citizen Andrew Brunson, Shaheen’s office said.

Brunson, a Christian pastor who could be jailed for up to 35 years, denied terrorism and spying charges in a Turkish court this month. He has been in pre-trial detention since 2016.

It also faults NATO ally Turkey for its agreement with Russia in December to buy S-400 surface-to-air missile batteries. Ankara wants the system to boost its defense capabilities amid threats from Kurdish and Islamist militants at home and conflicts across its borders in Syria and Iraq.

According to Shaheen’s office, the intention to purchase the Russian system is sanctionable under US law.

“There is tremendous hesitancy (about) transferring sensitive F35 planes and technology to a nation who has purchased a Russian air defense system designed to shoot these very planes down,” said Senator Shaheen.

Relations between Ankara and Washington have been strained over a host of issues in recent months, including US policy in Syria and a number of legal cases against Turkish and US nationals being held in the two countries.

Turkey has said it would retaliate if the United States enacted a law halting weapons sales to the country.

Turkey plans to buy more than 100 of the F-35 jets, and has had talks with Washington about the purchase of Patriot missiles.

The move to buy S-400s, which are incompatible with the NATO systems, has unnerved NATO member countries, which are already wary of Moscow’s military presence in the Middle East, prompting NATO officials to warn Turkey of unspecified consequences.

The NDAA is several steps from becoming law. The House of Representatives passed its version of the legislation earlier on Thursday. The Senate must still pass its version of the bill and the two versions must be reconciled before a final compromise bill can come up for a vote in both the House and Senate later this year.