Beirut, Lebanon (CNN) -- Syrian rebels call them "wizwayzi," humming eyes in the sky they say guide the government warplanes and gunners who bombard their positions.
They're surveillance drones, easily visible from the ground and seen in video shot by rebel fighters. Syrian opposition activists and rebel commanders say both the tempo and accuracy of airstrikes have increased since government forces began using them -- and they point to Iran as the source of the equipment.
"Of course it's Iranian. It doesn't go up that high. We can see it," Muhiyee Deen al-Zein, a Free Syrian Army leader in Homs, told CNN.
"They say, 'The wizwayzi is out.' It's a small drone that films al-Qusayr, and then you think, 'Oh God, help al-Qusayr, it will sleep under rockets.' "