Turkish President Recep Tayyip Erdogan said Friday that it would be “disrespectful” for the Trump administration to sanction a fellow NATO member, after reports this week suggested sanctions for his country’s purchase of Russian-made air defense systems were imminent. 

Reuters reported Thursday that the outgoing administration will impose the long-awaited sanctions, with sources telling the news agency an announcement could come any day. 

Turkey tested the Russian-made S-400 system in October; the United States says the system poses a threat to NATO’s air defense capabilities and may compromise the security of its own F-35 stealth fighter jets. Washington booted Turkey from the joint strike fighter program last year and has repeatedly warned Ankara it risked congressionally mandated sanctions. 

The expected sanctions would be implemented under the Countering America's Adversaries Through Sanctions Act (CAATSA), a sweeping 2017 law that allows for financial penalties on countries that purchase Russian military hardware. President Donald Trump’s planned sanctions would target Turkey's Presidency of Defense Industries and the institution’s head, Ismail Demir, sources told Reuters.