Russia continues to build its military presence in Syria as fresh reports indicate that it has moved its first fighter jets to a growing base in Syria, defense officials said Friday, raising new concerns Moscow is preparing to play a direct role in helping embattled President Bashar al-Assad against Islamic State militants. Moscow’s military moves came as U.S. Defense Secretary Ash Carter spoke to his Russian counterpart about Russia’s deepening role in Syria, ending a long pause in high-level military ties between the two countries.

Defense officials said at least four tactical fighter jets had arrived at the rapidly expanding airfield on the Syrian coast south of Latakia. Over the past two weeks, defense officials said, Russia has dramatically stepped up development of the airfield by sending in housing for up to 2,000 people, attack helicopters, choppers to transport troops around the country, and artillery. FULL REPORT