Unmanned drones have become the weapon of choice in the Obama administration, which launched more drone attacks in nine months than the Bush administration did in three years. When it comes to attacking al-Qaeda, said CIA director Leon Panetta, drones are "the only game in town."

With drones, operators sitting in front of computer monitors in Virginia and Nevada can target enemies halfway around the world. When their shift is done, drone operators retire to their suburban homes.

The U.S. has several drone programs. One is controlled by the military and operates in countries where the U.S. is at war- Iraq and Afghanistan. A CIAcontrolled program targets terrorists in places like Pakistan and Somalia. The Homeland Security Department also uses drones to patrol the border with Canada.

The CIA program is the most troubling, since it operates outside the normal rules of military engagement. It is essentially a sophisticated program of political assassination-a practice President Ford banned by executive order in 1976.

Though drone attacks have taken out terrorist leaders and disrupted the activities of al-Qaeda, they raise troubling questions to those committed to the just war principle that civilians should never be targeted. Though perhaps more accurate than an airplane bombardment, drone attacks still result in a high level of civilian casualties. Thirty-two percent of those killed in drone attacks since 2004 have been civilians, according to the New America Foundation. A report in the New York Times a year ago claimed that for every legitimate target killed by a drone, 50 civilians are killed.

According to the just war principles, it is better to risk the lives of one's own combatants than the lives of enemy noncombatants. But this moral calculus is completely tossed aside in the case of drone warfare, since drone operators don't risk their Uves at all.

There are consequences in using drones, even if the weapons seem like a risk-free option. Drone attacks on civilians have given militants a recruitment tool. "Everyone of these dead noncombatants represents an alienated family, a new desire for revenge, and more recruits for a militant movement that has grown exponentially even as drone strikes have increased," co-wrote David Kilcullen and Andrew Exum, former advisers to General David Petraeus in Iraq and General Stanley McChrystal in Afghanistan, respectively.

Warfare has always been about the search for strategic and tactical advantages. Already there is a robotic arms race, with about 40 countries at some stage of testing or deploying unmanned weapons. Drone warfare no doubt strengthens militants' resolve to secure weapons of mass destruction to use against the U.S. The use of drones may well come back to bite us.