Syrian activists say Russia is expanding the tarmac of an airport in Syria's coastal province of Latakia.
The Britain-based Syrian Observatory for Human Rights said on September 13, "Russian forces are building a long runway capable of accommodating large aircraft near the Hemeimeem military airport."
"It could mean there will be more supplies or that they want to turn it into an international airport," observatory director Rami Abdel Rahman said.
The claim comes amid rising concern among U.S. officials of increased Russian military activity in Syria.
Russia, a key ally of Syrian President Bashar al-Assad during the country’s four-year civil war, says its increased military activity is part of the international effort to defeat terrorism.
Foreign Minister Sergei Lavrov said on September 13 that Moscow will continue sending military supplies to Syria.
"There were military supplies, they are ongoing, and they will continue,” Lavrov said in an interview with a Russian television news show. "They are inevitably accompanied by Russian specialists, who help to adjust the equipment, to train Syrian personnel how to use this weaponry.”
Washington has warned the Russian military buildup in Syria could lead to a "confrontation" with the U.S.-led coalition carrying out air strikes against the Islamic State extremist group.
U.S. President Barack Obama said on September 11 that Russia's support of Syrian President Bashar al-Assad is "doomed to fail."
With reporting by AFP, AP, Reuters, and Interfax