“We offer the U.S. to establish a technical working group with NATO’s inclusion and NATO can lead this technical working group actually. And this offer is still on the table,” Reuters reported Turkish Foreign Minister Mevlut Cavusoglu as saying at a virtual Atlantic Council event.

Washington threatened Ankara with sanctions and suspended Turkey from the program to build and operate the latest F-35 jets last year after Turkey bought the S-400s, which the United States says are not compatible with NATO systems and threaten the stealth capabilities of the new warplanes.

Turkey has disputed this and said that the S-400s will not be integrated into NATO’s defenses. Turkey had previously said it would make the Russian missile defense systems operational in April, but there has yet not been any sign of such a move, said Reuters.

Cavusoglu also said Turkey was still willing to purchase United States’ Patriot long-range air defense missiles.

Turkey this year asked for the deployment of the Patriot missiles on its southern border with Syria to help it confront the Russian-backed Syrian government’s offensive there. Washington has repeatedly said it will not provide Patriot missiles to Turkey unless it reverses its decision to buy Russian S-400s.

During a meeting in Washington in November, Turkish media said President Recep Tayyip Erdogan had agreed with U.S. President Donald Trump to set up a working group to resolve the issue, but it has not come to fruition.

Reporter’s code: 50101