Washington hopes Moscow did not deploy S-300 air defense systems in Syria because that would lead to a serious escalation of the situation, US Department of State spokesperson Heather Nauert said during a press briefing on Tuesday.
"I cannot confirm that that is accurate. I hope that they did not, that would be a serious escalation and concern," Nauert said when asked about the administration's reaction to reports Russia had sent S-300 systems to Syria.
Earlier, Moscow had announced that it would provide Syria with the S-300 as part of its response to the downing of a Russian Il-20 plane in Latakia with 15 airmen onboard.
Meanwhile, US spokesman Colonel Sean Ryan has stated that Russia's decision to provide Syria with S-300 systems has had no impact on US-led forces on the ground. "It hasn't changed anything," Ryan said.