But more and more weight is being accorded the theory that, even if bin Laden were to blame, his operation was state-sponsored.
Many experts point to an old foe with whom the United States went to war a decade ago - Iraq.
He noted the FBI's original theory in the investigation of the first attempt to blow up the World Trade Center in 1993 was that Saddam Hussein and Iraqi intelligence agents were behind it. However, federal prosecutors ultimately blamed a blind Egyptian cleric - Sheik Umar Abdal Rahman and 15 of his extremist followers. Powell and other American officials noted Thursday that, unlike other nations in the Middle East, Iraq has failed to express any condolences for the huge loss of civilian life Tuesday. He was indicted by a federal grand jury two years ago for allegedly directing the 1998 bombings of U.S. embassies in Kenya and Tanzania that killed 224. Shortly thereafter, he called upon Muslims to kill American citizens around the world.