Mark Mazzetti is shedding light on America's "secret army" in his upcoming book, The Way of the Knife. Obama finds himself in hot water these days over the constitutionality of his continued use of drones to carry out hits abroad. The CIA has its own personal drone fleet in addition to that of the military. Obama has expressed himself that he would like to see the two folded back into one, but continues to favor these surgical strikes against believed terrorists.
The use of drones is nothing new. Remotely piloted vehicles, or RPVs, go back to the 50s but were primarily used as surveillance planes. It was during the Vietnam War that RPVs began to carry missiles and were used for air strikes. The newest generation of drones were extensively used under the Bush administration, but Obama has extended the "drone armada" even further, as Oliver Stone noted in his last episode of the Untold History of the United States, using it to police the world's air space.
Mazzetti calls it a "shadow war" carried out by the CIA that has resulted in growing concern over the US reliance on drones to carry out what essentially amount to extralegal executions, including those of American citizens who have joined one or another terrorist group abroad.