The rules of war (which evolved from the Geneva Convention) cover it.As far as I know, the US isn't in a state of war with Pakistan. A 'war' in this definition requires there to be two nations involved. Hunting international criminals inside another sovereign state is not a war.
Which nations has America declared war against at the moment?
This also means it can't be a "war crime". Instead it's just a violation of Pakistani law (crossing the border without permission, weapons possession, use of explosives, trespass, break-and-enter, GBH, quadruple murder...). Pakistan sure as hell isn't going to do anything about this violation of their sovereignty though, because like you were saying, words like "illegal" become difficult when dealing with a rogue state armed to the teeth with WMDs.
Also, isn't it US policy that terrorists are "unlawful combatants" and aren't covered by the laws of war? i.e. They are not enemy soldiers captured during war, which instead, according to convention, places them under the jurisdiction of the detaining state's domestic law (which in practice means an American military tribunal)?
While killing bin laden was morally wrong and probably even illegal when considering international law i still think it was the right thing to do when looking at things pragmatically, holding him captive would most likely result in alot of terrorist activity aimed at forcing the US to release him which would be a very bad thing for US citizens in generalThe European international courts would've been happy to give him a trial -- in fact it would've been seen as a ridiculous show-trial if the Americans had done it themselves.
Ofcourse this also assumes that pakistan gave their permission for the operation (If not it would have been a violation of their sovereignity, but given the rather good US-Pakistan relations since 2001 I assume they did allow it.They've publicly said that they did not give permission for the operation, and weren't even informed until afterwards. I wouldn't call them "good relations" either - cooperating with the US is a very tense and harmful necessary evil for them.
He's had a public price on his head dead or alive for 10 years and as far as I can tell they ran in the front door guns blazing. That's not really an assassination.They ran in guns blazing, so it's not an assassination? They offered a cash reward in an effort to incite someone to kill him, so it's not an assassination? What???