Is sabotage of one's enemy in wartime ethical? Of course. Deception is one of the best tools in the arsenal of a winning military force.
The Improvised Explosive device is the most deadly killer of American soldiers. In 2004, we could have likely greatly curbed the number of such deaths, if we had gone ahead with some sabotage technology:
The insurgents who kill our young soldiers are ruthless, but we have sometimes been cautious in our response. Take the question of targeting bomb makers: There may be an unlimited supply of explosives in Iraq, but there is not an unlimited supply of people who know how to wire the detonators. In 2004, CIA operatives in Iraq believed that they had identified the signatures of 11 bomb makers. They proposed a diabolical -- but potentially effective -- sabotage program that would have flooded Iraq with booby-trapped detonators designed to explode in the bomb makers' hands. But the CIA general counsel's office said no. The lawyers claimed that the agency lacked authority for such an operation, one source recalled.
Instead of having short-circuited one of the least discriminating killers (probably more civilians are killed than soldiers by IEDs), we spend a great deal of time defusing a plethora of bombs that might not have been placed.
A fair number of roadside bombs are placed by poor Iraqis just trying to make a buck. It's easy, it pays well, and it pays even better if your bomb disables equipment--and especially if it kills US troops. If a sudden rash of unexplained IED-setter deaths had occurred in 2004, these people would have found other sources of income.
Not only would the sabotaged IEDs have been "deactivated", there would be far fewer of them being emplaced today.