The United States has urged Turkey to abandon the purchase of the S-400 anti-aircraft missile system from Russia, warning Ankara of the consequences of its decision, Haberturk reported citing a source in Washington.

According to the Turkish newspaper, an unnamed American official expressed his concerns over Ankara’s purchase of Russian surface-to-air missile systems, explaining that they could “negatively influence the interoperability of NATO” and assuming that Washington could impose sanctions in response to the recently adopted law.

“We want to help Turkey find a better alternative to meet its air defense needs,” the official said, according to Sputnik International.

Earlier in February, Turkish Foreign Minister Mevlut Cavusoglu spoke out against the language of threats regarding its purchase of the S-400 systems.

The U.S. State Department has previously threatened to apply “appropriate measures” against countries willing to buy Russia’s S-400 systems.