U.S. senators have moved for a second time to block delivery of F-35 stealth fighter jets to Turkey unless it abandons an arms deal with Russia, even as the plane's manufacturer announced the roll-out of the first aircraft purchased by Ankara.
The Senate Appropriations Committee passed a spending bill for U.S. foreign operations on June 21 after adding an amendment blocking delivery of the F-35s unless Turkey drops its plans to buy Russian S-400 missile-defense systems.
A similar measure blocking the F-35 sales to Turkey was added to a massive defense bill that passed the Senate on June 18.
Washington and its NATO allies have expressed concerns for months over Turkey's 2016 agreement to buy the S-400, warning that the Russian system is not interoperable with NATO and U.S. military equipment.
Some legislators also fear that if Turkey uses the highly advanced U.S. jets alongside the S-400 systems, Russia may gain access to sensitive and secret technologies used in the aircraft.
"The concern is that the F-35 is the most advanced aircraft, the most advanced NATO aircraft, and if Turkey goes forward with the acquisition of the S-400, it will allow the Russians to collect information on how to best attack an F-35 fighter," said the sponsor of the Senate appropriations amendment, Senator Chris Van Hollen.
"The Russians could more easily evaluate the capabilities of the F-35 and detect and exploit its vulnerabilities. That is unacceptable," he said.
Turkey has largely dismissed the concerns raised by U.S. and NATO officials and has refused to cancel the Russian deal. On June 19, Turkish Prime Minister Binali Yildirim criticized the Senate amendments and warned that Turkey had "alternatives" if the F-35 sales were blocked.
Ankara had plans to eventually buy more than 100 of the F-35 Lightning II fighters.
The plane's manufacturer, Lockheed Martin, announced the roll-out of Turkey's first two F-35s in an official ceremony in Fort Worth, Texas, on June 21.
Turkish pilots were given access to the aircraft at the ceremoney, but they will not be allowed to transport them to Turkey until they have been trained to fly them over a period of months that could last up to two years, U.S. defense officials said.
The roll-out ceremony in Texas was attended by company executives, Turkish defense officials, and Pentagon officials.
At the event, Turkish Major General Reha Ufuk Er said that Turkey's F-35s were "a great asset to thwart future threats" and would contribute to global stability.
Turkey's deputy undersecretary of defense industries, Serdar Demirel, said that the F-35s would help the country "strengthen the deterrence of NATO."
The Pentagon has not officially weighed in on the Senate moves to block the F-35 sales, but CNN reported that U.S. Defense Secretary James Mattis opposes the measures and is working to have them dropped from the Senate's defense and foreign-operations bills.
While the Senate bills target Turkey's F-35 purchases, the House version of the defense bill, which was passed in May, would stop all U.S. weapons sales to Turkey until the Pentagon analyzes the implications of worsening tensions between Washington and Ankara.