BEIRUT (AP) -- Syrian activists say Russian troops are expanding a military base in central Syria, adding fortifications and developing its runways in a sign they intend to use it as their second air base in the country.
The work underway in the Shaayrat air base could also signal Moscow's intention to step up airstrikes in the country's central region where the Islamic State group is active.
The base is about 40 kilometers (25 miles) southeast of the city of Homs.
Bebars al-Talawi, a Homs-based activist, and Rami Abdurrahman, director of the Britain-based Syrian Observatory for Human Rights, both reported the Russian activity on Thursday.
Russia has been conducting airstrikes in Syria since Sept. 30, using the Syrian government's Basel al-Assad air base in Latakia province.