An Airbus Defence and Space satellite image courtesy of Stratfor, a geopolitical intelligence and advisory firm in Austin, Texas, shows at least 16 Russian combat aircraft stationed at the Bassel al Assad air base near the Syrian town of Latakia September 20, 2015. Russia has started flying drone aircraft on surveillance missions in Syria, U.S. officials said on Monday, in what appeared to be Moscow's first military air operations inside the country since staging a rapid buildup at a Syrian air base. Mandatory Credit REUTERS/www.Stratfor.com/Airbus Defense and Space/Handout via Reuters ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. NO SALES. NO ARCHIVES. MANDATORY CREDIT

WASHINGTON (Reuters) - Satellite photos taken in mid-September and obtained by IHS Jane’s show Russian forces developing two additional military facilities near Syria’s Mediterranean coast, Rob Munks, editor of IHS Jane’s Intelligence Review, said on Tuesday.

Munks said the previously undisclosed work was taking place at a weapons storage facility and a military base north of Latakia, suggesting Russia is preparing to place troops at both locations.

Russia has been dramatically increasing its forces at an air base south of Latakia, a stronghold of Syrian President Bashar al-Assad, including positioning combat planes and helicopters as well as tanks and accommodation blocks.

Washington has been wary of Moscow’s support for Assad and U.S. officials have said such deepening ties are troubling even as the United States and Russia have their eye on fighting the Islamic State militant group.

Jane’s, a defense intelligence provider, acquired the images from a commercial satellite division of Airbus Group SE, according to the Wall Street Journal, which first reported on the imagery.

Munks told Reuters one of the sites was located about 4 miles (7 km) north of Latakia and the second was 2 miles (3 km) west of that. The images showed construction of new buildings and grading of terrain, as well as the presence of new tents typically used by Russian military units.

One of the facilities is adjacent to a surface-to-air missile site, Munks added.