Two F-15Cs RC-Pro Photography Russia's military intervention in Syria in support of the regime of Bashar al-Assad has made US operations in the country more complicated. Although both countries are purportedly fighting ISIS, their larger strategies are at cross-purposes in Syria, where the US advocates a political transition in which Assad eventually steps down.

Now, in the latest sign of growing tensions between the US and Russia in Syria, the US is sending planes equipped only with air-to-air weaponry to the region, David Axe reports for The Daily Beast. As Axe notes, Russia's the only potential US adversary in Syria with its own combat aircraft.

The Pentagon announced last week that it would send up to a dozen F-15Cs to the Incirlik Air Base in Turkey for operations over Syria. As The Daily Beast notes, the aircrafts' exact role remains unclear.

F-15Cs are armed with only air-to-air weaponry, making the plane unnecessary in operations against ISIS, which doesn't have a functioning air element. Instead, the jets could have one of two purposes in the region — they could either be used to help protect Turkey's border against periodic incursions by Syrian jets and helicopters.

Or, under certain circumstances, the F-15Cs could be used to help counter Russian activity over Syria. A hypothetical no-fly zone over northern Syria near the Turkish border, for instance, would have to be maintained using planes that could enforce the zone against both Russian and Syrian aircraft.

"Such a zone could compel F-15s and other U.S. planes to directly confront Russian planes, even though — in theory— both air forces are attacking ISIS," Axe writes. "Russia and the United States do make efforts to steer their jets away away from possible collisions, but otherwise do not collaborate in their separate air wars in Syria."

The introduction of the F-15s highlights the danger of a potential confrontation between allied and Russian aircraft in the Middle East, regardless of whether such an escallation would be intentional or accidental.

In the beginning of October, an unnamed British military official told The Sunday Times that British jets had the go ahead to engage Russian aircraft over Iraq or Syria if fired upon or if they felt their life was endangered. However, the British government quickly denied the report.

Russian jets have also shadowed US MQ-1 Predator drones as they have conducted operations over ISIS territory, including above ISIS' de facto capital of Raqqa and near the Syrian-Turkish border.

During operations, US and Russian jets have come within 20 miles of each other in the air. This was close enough that the planes could see each other in their targeting cameras. At such close ranges, the potential for accidents — or for a fateful misunderstanding — sharply increases.