Yes, it’s the empire and the oil, and yes, people in government love to kill and destroy—it’s the ultimate expression of their power lust, that they can visit foreigners with death from the skies. But here is an additional reason: a new war takes everyone’s eye off the financial ball, and makes them forget the looming crisis. The deficits and dollar weakness have harmed the prestige of the State. Nothing like some dead bodies to cheer up the US citizenry and to make the government seem effective. See Wag the Dog.