1) The US Army is scared of the repeated left-wing electoral victories in Latin America, and the potential to cut off "US" oil. This contrasts with US glee at right-wing military victories in the good old days.
2) How much oil does Kuwait really have? Probably not as much as we're banking on. As in, maybe half.
3) Finally, and most terrifyingly, Matt Simmons (author of Twilight in the Desert) sez "the Energy Crisis is here" (large PDF) and predicts that by 2018, Middle Eastern oil production will decline by 50%. Given that the Middle East is the only province not declining as we speak, that means global oil production probably below 70 million bpd, attempting to meet demand projected to be over 100 mbpd.