Turkish President Recep Tayyip Erdogan said Wednesday it was “out of the question” to reconsider a controversial deal to buy a top-line Russian anti-missile system and he might even look at other purchases. The United States, a long-standing NATO ally and supplier of much of Turkey’s military equipment, has pressed Ankara to drop the S-400 deal, saying it is incompatible with its established weapon systems and is part of Russian efforts to muddy the waters in a key, volatile region. “As for the S-400, the deal is done and it is out of the question to go backwards… and perhaps after the S-400, we will move onto the S-500,” Erdogan told Kanal 24 television.