“The S-400 Air Defense Systems are in our inventory. There is no change in our stance on the S-400,” Aktürk said, at a weekly Türkiye Defense Ministry briefing in Ankara. Türkiye, a NATO member, purchased two Russian S-400 air systems in 2017 at a reported cost of $2.5 billion and took delivery on them in 2019. According to Turkish media reports, the Turkish military never fielded its S-400s, which are not compatible with NATO combat aircraft or air defense systems. The most recent possible Ukrainian attack against a Russian S-400 system probably took place on Sept. 15-16, in Russia’s Saratov region.