What does Islam say about suicide bombing, hijackers, and terrorism in general?

God tells us in the Quran that we shall not kill ourselves, that life is sacred, and that we shall not aggress. If an enemy aggressive and fights us, we can defend ourselves but we have no excuse to fight them if they decide to refrain. Also, we must not kill another believer; so before we strike we have to be absolutely sure. All of this put together means that suicide bombing, hijackings, and terrorism are non-Islamic.