The drone strikes being conducted in those three countries are not being done to challenge those states, but to supplement the power of those states, to act when they cannot or will not. More importantly, these are precise strikes against certain individuals, making them more like police work than like classic military action. Police work involves small arms used precisely. Drones aren't pistols, but firing one Hellfire at a Land Rover is more like a police action than it is like a large-scale military offensive with artillery barrages, armored columns, and infantry assaults. (Yes, I am shifting my position a bit from what I wrote recently about Libya.)
We all understand that drone aircraft have changed warfare, but I suspect they also are changing diplomacy and foreign relations. Drones, like cruise missiles before them, have made it much easier to use force internationally. But doing this does not mean we are at war. - Thomas Ricks
Really? If Iran suddenly developed the wherewithal to fly a drone over suburban Virginia and blew up the house (and wife and kids) of a man it claimed was in the CIA conducting a terror campaign against Iranian nuclear scientists, I think the U.S. would consider that bombing an act of war, or at the very least an act of terrorism. It certainly wouldn't consider it "police work."