Congress is moving forward with a major defense bill.

The House passed a bill Thursday that would do a number of things: authorize low-yield nuclear weapons on submarines, increase troop pay, authorize 13 new Navy battleships and add more than 15,000 active-duty military members.

But a part of the bill that has been getting a lot of attention is a temporary ban on F-35 fighter jet sales to Turkey.

Turkey is a member of NATO and a partner in the fight against ISIS. But Congress has frowned on the country’s plan to buy a missile defense system from Russia. Turkey’s move toward authoritarianism under President Recep Tayyip Erdoğan also seems to be a concern.

But Defense Secretary Jim Mattis argued for the deal to go through. He wrote to members of Congress saying a ban on new jet sales to Turkey would disrupt the international supply chain, raise costs and affect delivery times. Bloomberg reports at least 10 Turkish companies make parts for the F-35.

The bill would ask the Pentagon to report on its assessment of the sale within 90 days of its passage.