State Department calls S-300 transfer, if confirmed, 'serious escalation'

Russia said on Tuesday that it has delivered an S-300 surface-to-air missile system to Syria, in defiance of Israeli and US concerns that the arms sale would embolden Iran and escalate the Syrian war.
In Washington, State Department spokeswoman Heather Nauert could not confirm reports the S-300 had been delivered.
"I cannot confirm that that is accurate. I hope that they [the Russians] did not," she told a press briefing. "That would be, I think, sort of a serious escalation in concerns and issues going on in Syria, but I can't confirm it."