There are a lot of reasons why it would mostly not be a good idea to go around carelessly assassinating foreign heads of state. It’s going to generate a LOT of ill will that will make the faked up outrage over Abu Ghraib look like a valentine.
Still, the possibility of such an action has strong moral weight under some circumstances. Under what system of morality would it NOT be superior to kill a few deserving offenders if you could rather than have a full scale war?
Yes, it would be the PR nightmare from hell for US to send a hit squad after a foreign head of state, but being labeled the bad guy might be less bad than, say, letting Iranian mullahs get nuclear weapons.
There’s one major legal issue, though: It’s illegal under US law for our agents to perform assassinations. As Alan Colmes played the liberal trump card against an apologist for Rev Robertson’s remarks about assassinating Hugo Chavez, “You do believe in the rule of law, don’t you?”
The relevant law is Executive Order 12333, most specifically Part 2, Section 11: “2.11 Prohibition on Assassination. No person employed by or acting on behalf of the United States Government shall engage in, or conspire to engage in, assassination.” You have to admit, that’s pretty clear.
Thing is, this is merely an executive order, ie something the president made up on his own accord. It is not part of the US Constitution, nor was it even a law passed by Congress.
Therefore, President Bush could and should perfectly well simply rescind that provision what ties our hands behind our backs of his own accord with another executive order.
Plus, even if we don’t actually use it, the hanging possibility of assassination COULD conceivably happen to be just the thing to make Kim Jong Il or some Iranian mullahs become more open to reasonable negotiation. OK, so maybe they could calculate that we won’t start a wholesale war, but the possibility of US coming after them personally might get their attention.