AlQa'dah 22, 1436, September 06, 2015, SPA -- The United States for the first time Saturday directly complained to Russia about reports of its military build-up in Syria, but has not yet officially confirmed the Russian presence in the war-torn country, dpa reported. US Secretary of State John Kerry delivered the warning in a telephone call with Russian Foreign Minister Sergei Lavrov aimed at discussing US concerns "about reports suggesting an imminent enhanced Russian military build-up there," according to a statement from the State Department. "The Secretary made clear that if such reports were accurate, these actions could further escalate the conflict, lead to greater loss of innocent life, increase refugee flows and risk confrontation with the anti-ISIL [Islamic State] Coalition operating in Syria," according to the document. According to The New York Times on Saturday, Russia has delivered a portable air traffic control system and prefabricated housing units for hundreds of people at a Syrian airfield. It cited unnamed administration officials. In addition, the Russians have filed military over flight requests across bordering countries throughout September, the story said. On Friday, Putin did not expressly exclude the deployment of Russian soldiers in the fight, but he indicated the issue was not yet on the agenda, according to the Interfax news agency. In the telephone call on Saturday, Kerry and Lavrov agreed that discussions on the Syrian conflict would continue in New York later this month, the US statement said.