The U.S. has proposed forming a joint working group with Turkey to discuss the former’s imposition of CAATSA Sanctions over Ankara’s S-400 buy.

“The proposal to set up the Turkish-U.S. working group came from the American side. Because we support dialogue, we said ‘yes’ to the proposal, and the negotiations at the level of experts have started,” Turkey’s Foreign Minister Mevlüt Çavuşoğlu said during the year-end news conference today.

Turkey has earlier proposed a working group to assess the potential impact of the S-400s on NATO systems, a suggestion initially ignored by Washington.

U.S. Secretary of State Mike Pompeo announced a series of sanctions under the Countering America’s Adversaries Through Sanctions Act (CAATSA) against Turkey’s military procurement agency (SSB) and four senior Turkish officials for its S-400 buy on December 14. They prohibit the SSB from importing or exporting to U.S. entities. Since the SSB is the main coordinating agency for all defense projects including that of international sales, sanctions against it may impede Turkey’s ability to manufacture and export defense goods.

“In our meeting with Pompeo, we said our proposal still stands. The Americans said let’s work together on this issue. It (sanctions) is an attack on our sovereign rights,” Çavuşoğlu added.

A day earlier, Jens Stoltenberg, Secretary General of NATO, reiterated his earlier statement that Turkish S-400s not only posed a threat to alliance’s aircraft, it also was not possible to integrate with their air defenses.

Pompeo told Cavusoglu earlier that Turkey’s purchase of the S-400 system endangers the security of U.S. personnel and military technology and allows Russian access to the Turkish armed forces and defense industry. He “stressed that the goal of the sanctions is to prevent Russia from receiving substantial revenue, access, and influence,” State Department spokesperson Cale Brown said on December 18.

“….they (sanctions) are not intended to undermine the military capabilities or combat readiness of Turkey or any other U.S. Ally or partner,” Pompeo told the Turkish minister.