OK...so, you're the president of the USA and you want to get re-elected in a few years. First, you arrange for 4 airplanes to dissapear entirely (including hundreds of people who have to be silenced - permanently), you kidnap the planes and replace them with 3 airplanes and one large truck-bomb), with two of the new planes, loaded with missiles and explosives, not to mention explosives attached to the side of buildings, you destroy two large towers in New York, the third plane, you crash harmlessly into farmland, the truck, you blow up next to the Pentagon). You quickly blame a country who you hate and is relativly easy to invade.
With the death of several thousand people (men, women and children), plus the money spent on those fake planes, plus the repair of all that damaged property, plus the removal of those damn witnesses etc etc and the $b spent on the war itself etc... you've 'maybe' secured yourself another 4 years in office.
Seems plauseable to me.