New US legislation which threatens to cancel Turkey’s involvement in the F-35 program prompted a terse response from Ankara on Friday.

Following the bill’s passage in committee on Thursday, Turkish foreign ministry spokesperson Hami Aksoy said that preventing the sale of F-35s to Turkey is “against the spirit of [Turkey’s] alliance with the US,” according to Hurriyet news.

“This is not a program managed solely by the US. It is a multinational program and we expect everybody to fulfill their obligations,” Aksoy said. He added that Turkey has “fulfilled its obligations” regarding the F-35 program.

If the US takes such steps “we will have to respond,” he stressed.

The bill – an amendment to the National Defense Authorization Act – was crafted in response to the detention of US citizen Andrew Brunsen, who faces up to 35 years in a Turkish prison on terrorism and spying charges, Reuters reported.

The amendment also cites Turkey’s signing of an agreement with Russia last December to purchase S-400  surface-to-air missile systems.

“There is tremendous hesitancy (about) transferring sensitive F-35 planes and technology to a nation who has purchased a Russian air defense system designed to shoot these very planes down,” said Senator Jeanne Shaheen, one of the bill’s cosponsors.