While they recognize that worsening U.S. relations with Turkey in recent years and Russia’s growing clout with Ankara may also have helped sway Turkey toward buying the S-400 system, three U.S. officials and a defense source told Reuters of another working theory that has gained ground within the Trump administration.
One reason Erdogan may have chosen to buy from Russia rather than from a fellow NATO member is that he might be wary of his own air force, which played a major role in the coup attempt on July 15, 2016, these officials say.
S-400 missiles, which Turkey began taking delivery of last Friday, would be better at fending off any attack on the Turkish government from its own jets than a U.S.-supplied Patriot system would, experts say.
Raytheon Co’s’s Patriot missiles, which have been on offer to Turkey, would have safeguards to help avoid "friendly fire" against other NATO warplanes, such as Turkish air force jets.