US Treasury Secretary Steven Mnuchin says the Trump Administration is considering the possibility of imposing sanctions on Turkey for its purchase of an advanced Russian-made air defense system. “We’re looking at that,” he told reporters outside the White House on Monday. “I’m not going to make any comments on any specific decisions, but we are looking at it.” Ankara, a member of NATO, purchased S-400 ground-to-air missiles, whose delivery began in mid-July. The purchase contravened alliance doctrine that calls for member states to use defense systems that are compatible with those used by other members. It also angered Washington, which had wanted to sell Turkey US-made Patriot air defense missiles. In response, the Trump Administration effectively canceled a decision to supply Turkey with the US-made F-35 advanced stealth fighter, saying it feared that Russian technicians ostensibly sent with the S-400s could learn some of the fighter’s secrets.