"It is generally assumed that an act of war can only follow a formal declaration of war." Haha People's ideas about what a war is are always 50 years out of date. It is the same reason WW I was fought with 19th century tactics and 20th century weapons which is part of what made it such a drawn out mess.

I think it is difficult to really pin the issue down. Some of it is about power. Some is about regaining lost empires or growing existing ones (though in a non-traditional form). However there could easily be more than we are aware of behind the scenes (or right out in the open) too. Take for example, the christian fundamentalists in the U.S. government (and there are more than a few). They, for religious reasons, believe that the Jews must control the "holy land" in order for their prophecy to be fulfilled and the use their power to push for policies that would make that more likely to happen by opposing other powers in the reason who are not aligned with Israel. This is one of the reasons that I believe that the conservative party (which tends to be more religious) has been pushing for war with Iran for the last decade. It could get even crazier too but I don't want to venture too deeply into "conspiracy" territory lol.