The Biden administration believes a potential sale of F-16 fighter jets to Turkey would be in line with U.S. national security interests and would also serve NATO’s long-term unity, the State Department said in a letter to Congress that fell short of explicitly supporting the deal.

Turkey made a request in October to the United States to buy 40 Lockheed Martin-made F-16 fighters and nearly 80 modernization kits for its existing warplanes. Washington has so far refrained from expressing any opinion on the sale, saying it needs to go through the standard arms sales process.

The sale of U.S. weapons to NATO ally Turkey became contentious after Ankara acquired Russian-made defense missile systems, triggering U.S. sanctions as well as Turkey’s removal from the F-35 fighter jet program.

The State Department letter, first reported by Reuters, is dated March 17 and signed by the agency’s top legislative official Naz Durakoglu. She acknowledges the strained relations while at the same time describing Turkey’s support for and defense ties with Ukraine as “an important deterrent to malign influence in the region.”

Read more: Reuters