First, it seems OK to assassinate a terrorist kingpin either by air attack or commando raid. But legal and moral problems arise if he is captured, detained, waterboarded or tried in a military tribunal. A quick death seems to end almost all legal discussions and controversies.
Second, there is also no problem in assassinating a foreign dictator as long as the mission meets two criteria: We must be engaged in some sort of conventional battle with his forces, and we have to kill him through aerial bombing. For some reason, vaporization by a bomb seems to raise fewer ethical issues than execution by a sniper's bullet.
Third, targeted assassinations are better done under liberal presidents, who are more likely to be seen as humanitarians who only reluctantly order such killings. The Bush antiterrorism protocols -- tribunals, renditions, preventative detentions, Predator assassination missions, Guantanamo Bay -- were decried as illegal and immoral. Such furor vanished, however, when President Obama embraced or expanded them all. The effort to preemptively remove the mass-murdering Saddam Hussein to foster democracy in his absence was seen by many in the media, universities and legal community as morally wrong -- and yet preemptively bombing Gadhafi to foster democracy in his absence is now considered morally justified.
Fourth, success seems to end moral ambiguity in much the same way failure invites it. Had we gone into Pakistani territory and landed in the wrong compound, legal and ethical issues would have been raised. If we keep killing members of the Gadhafi family without hitting Gadhafi himself, at some point the denial of targeted assassination will seem empty. Targeted assassinations apparently have to work on the first or second attempt to be deemed moral and legal.
In recent years the United States has been in a number of undeclared wars against terrorists, insurgents and authoritarian dictators -- Mohamed Farrah Aidid, Saddam Hussein, Osama bin Laden, Slobodan Milosevic, Khalid Sheikh Mohammed, Manuel Noriega, Mullah Omar, Muammar Gadhafi, the Taliban, al-Qaeda and others -- whom we sought to kill, capture or put on trial.
It is about time that we clarified the rules that determine their fates.