Russian warplanes have begun their own bombing campaign in Syria today, with official statements saying they are targeting ISIS to prevent the group from taking over any more of Syria. Other rebel factions, however, claim they are being hit as well.

The Free Syrian Army (FSA) claims Russian warplanes attacked them in the countryside of the Hama Province, launching a number of missiles at their “headquarters” in the area, and wounding eight fighters. They insist that there is no ISIS presence anywhere around the targeted area.

US officials similarly reported that Russia attacked the western part of the nearby Homs Province, and protested that the area isn’t believed to have ISIS fighters either. This isn’t necessarily true, however, as ISIS is believed to be among the factions fighting over the area around Homs itself, and the group has a heavy presence across eastern Homs Province, including Tadmur.

US officials were said to be “furious” about Russia hitting the FSA rebels, who were heavily armed and backed by the US until they’d lost virtually all of their territory. British officials similarly issued a warning to Russia to leave the FSA alone.

The location of the attacks, while not precisely reported, suggests Russia’s early strategy in the air campaign is to shore up positions belonging to the Assad government, particularly the area that links Assad’s primary power base along the coast with the capital city of Damascus. Preventing the collapse of this supply route is likely seen as vital to buying them enough time to go after ISIS in earnest.