Under skies crowded by the warplanes of half a dozen countries, an assortment of factions backed by rival powers are battling one another in a dizzying array of combinations. Allies on one battlefront are foes on another. The United States, Russia, Turkey and Iran have troops on the ground, and they are increasingly colliding.

In the space of a single week last week, Russia, Turkey, Iran and Israel lost aircraft to hostile fire. The United States, meanwhile, has been battling for days to hold back Iranian-supported Syrian tribal militias in the eastern desert, drawing U.S. forces closer toward entanglement in Syria’s conflict.

“The risks are high,” said Sami Nadir of the Levant Institute for Strategic Affairs. “There is a new Cold War prevailing in Syria and any escalation could pave the way for a regional or international war given the fact that the big powers are directly present on the ground and not through proxies, as used to be the case in the past.”