Oh, yes, definately.
As for me, I personally put assassination on a higher moral plane than war. If war is justified, then assassination is certainly justified.
Assassination isn’t just “The targeted killing of individuals in war.” Military leaders are often targeted - Yamamoto, for example. And snipers are all about picking out individuals and killing them.
Assassination in the context of a war is usually considered to be the directed killing of a non-combatant who is not in the chain of command. So if you can find a general and kill him, good work. But if you hunt down a political leader and kill him to attempt to intimidate the country or population, that’s an assassination.
My country, Canada, is especially good at sniping. We’ve killed a whole lot of terrorists in this war in Afghanistan, from thousands of meters away. It’s an accepted tactic in warfare. And it’s often directed at specific individuals - spot the guy who seems to be controlling the show, and kill him. Or you get word that a ranking al-Qaida or Taliban guy will be in the area, and you wait in an ambush position a thousand meters away and pick him off as he goes by.
In this case, these people are combatants. They’re in the chain of command. They’re issuing orders, raising armies, directing operations. Of course, in a war against terrorism it all gets a little fuzzy because the other side isn’t in uniform and the same person can be a mild-mannered businessman by day and a guerrilla by night. Some, like the various warlords affiliated with al-Qaida, are also political and maybe even religious leaders. But they’re still combatants.
Going after people who are attacking you in Iraq isn’t even the most controversial ‘assassinations’ the U.S. has done. A closer example to a real assassination would be the Predator strikes on terrorist leaders who aren’t anywhere near a battlefield. The U.S. gets intel that an al-Qaida leader will be traveling between two destinations in the Sudan or Libya or Pakistan, so they fly a predator into the area, look for his car, and bomb it. But even that’s okay in my book. Again, when the terrorists are out of uniform and not engaging on a standard battlefield, the rules have to change. Just as the rules change for spies. In WWII, if an enemy was caught behind your lines without a uniform, you could summarily shoot him. But if he’s in uniform, the Geneva convention for captured soldiers applies.