NATO and the United States have expressed concern over reports of growing Russian military activity in Syria.
During a visit to Prague on September 9, NATO Secretary-General Jens Stoltenberg said that, if confirmed, Russia's involvement would "not contribute to solving the conflict."
U.S. Secretary of State John Kerry called his Russian counterpart, Sergei Lavrov, to reiterate his concerns. Spokesman John Kirby said Kerry made clear to Lavrov that if the reports were true "it could lead to greater violence and are not helpful at all" to efforts by the international community to end the conflict.
Lavrov said on September 10 that Russian planes are sending to Syria “both military equipment in accordance with current contracts and humanitarian aid."
Russia, a key ally of Syrian President Bashar al-Assad during the country’s four-year civil war, acknowledges it has sent military experts to assist with Russian arms deliveries.
"Russia is not taking any additional steps at the moment, but if that is necessary we will be taking these steps" in compliance with its with international law, Lavrov said.
The United States is calling for Assad's removal.