they are angry bc in their warped understanding of the way the world works, their way of life and their ideals are being threatened by western ideals and western freedoms and western lack of islamic principles, and america being the poster child for the west and the free world, america is therefore a prime target, as well as the UK and other westernized countries in the EU, canada, and any other freedom of religion, freedom of speech countries....the mujahideen, or afghan freedom fighters against russia in the 70s and 80s LOVED america when it was arming them in their fight against the russians, now many of the old mujahideen fighters and their kin have strong ties to al queeda , now HATING america, go figure