Terrorists acts

Its just 5 years after most horrible terrorist attack ever. Group of islamic fanatics armed by blades flew with big aircraft into wtc, first they hit one tower and many speculations about terrible disaster went out, and than second part of building was hit. And all went clear, it wasnt possible to be disaster, it had to be terrorist attack. Buildings started to burn, and than after few hours they collapsed, burrying many dead bodies below. Reactions of people were different, some were frightened, some happy they werent there, and some were celebrating that US gained what they deserve. (Really, i still remember it. Hours after it happend, governments were sending words of compassion, but many people were happy, that somebody show to world, that even USA can be hit into nose by group of unwashed primitives.) Immediately world suspected Ben Laden's Al quaeda organisation to be responsible for this, but they didnt accepted it. Days after, there were many theories, about how it all happend, including facts, that CIA known all about prepared attack before, and they let it happend, so US have reason to attack their own enemies, and many similar. But what really happend? Probability of discovering truth between whole mountains of lies and propaganda is near zero.