The United States and Russia are talking to each other about Syria to ensure their forces in the unstable conflict zone avoid accidentally engaging each other.
U.S. Defense Secretary Ash Carter spoke to his Russian counterpart Friday for the first time since Carter took office seven months ago.
A senior Defense official said Russian Defense Minister Sergei Shoygu told Carter that Russia's activities in Syria are defensive in nature and that Moscow is just honoring commitments it made to the Syrian government.
The diplomatic move Friday represents a new initiative in the Syrian crises as the U.S. and Russia have been content until now to denounce each other about their respective roles in the conflict.
Seeking common ground
U.S. Secretary of State John Kerry, in London to talk with allies about options in Syria, said "We are looking for ways in which to try to find the common ground. Clearly, if you are going to have a political settlement, which we have always argued is the best and only way to resolve Syria, you need to have conversations with people and you need to find the common ground."
The talks between the two world powers happened just hours after news of Russia's military build-up in Syria appeared to be entering a new phase with the arrival of fighter aircraft.
Kerry will meet with some of his European counterparts Saturday to discuss the situation in Syria.
U.S. officials said Friday that Russia had deployed four Sukhoi attack aircraft to an air base near Latakia. Eight Russian helicopters have also been spotted.
"Moscow’s ultimate intentions are unclear but initial signs suggest a focus on providing air support to Syrian forces and to humanitarian relief operations," a U.S. intelligence official told VOA on the condition of anonymity because he was not authorized to speak about the matter publicly.
U.S. officials say Russia now has 500 naval infantrymen on the ground in Syria, with more on the way.