“If somebody could obtain reliable access to real-time Predator or Reaper video — without attribution or alerting U.S. military — that would a tremendous intel coup,” says Micah Zenko, a fellow at the Council on Foreign Relations. “There is an insatiable demand from Predator and Reaper imagery in Afghanistan and elsewhere. Any reluctance to use those for spying or missile strikes places operations in Afghanistan, Pakistan, Yemen, and Somalia at some risk.”

Military officials have known about — and mostly shrugged off — the vulnerability since the development of the Predator in the 1990s. But the problem drew increased attention in 2008, when drone video footage was found on the laptops of Shi’ite militants in Iraq, who were able to intercept the feed using a piece of $26 software. The Pentagon and the defense industry assured the public that they’d close the hole by retrofitting the robotic aircraft with new communications protocols and encrypted transceivers that would keep the video from being intercepted again.

Four years into the effort, however, only “30 to 50 percent” of America’s Predators and Reapers are using fully encrypted transmissions, a source familiar with the retrofitting effort tells Danger Room.