Conspiracy theories about the September 11th, 2001 attacks on the US are several. These are all attributed to understanding how these attacks were planned and executed. These theories go beyond the knowledge of the al Qaeda terrorist group whose responsibility was made evident later on. There is much debate about the attacks and whether the high-level government authorities in the US had the prior know-how on such attacks. There are several theories that have been formed though not all have been reviewed or undergone investigations by the government.
Those who have proposed these theories feel that there are inconsistencies in the conclusions that were made by the official authorities. They also feel that some evidence was overlooked or ignored about these attacks.
Among the several conspiracy theories, the one that is most prominent is how the collapse of the World Trade Center and the Twin Towers was a controlled demolition attempt. Even if the collapse as seen was brought about by the impact of the colliding airplanes and fire that resulted, many believe that it could have been planned from within. For instance, the hit on the Pentagon that is a highly protected landmark was probably initiated from inside the US government. A commercial airliner was probably allowed to do so as the American military and their vigilance was put down at such a time.
Conspiracy theorists have several other rife notions to suggest as well. For instance, it is felt that the invasions that the US did in Iraq and Afghanistan led to the retaliatory attacks on the US. The invasions of these countries were done on grounds of laying a natural gas pipeline that needed to go through Afghanistan. Many theorists are convinced that authorities in the US had advance knowledge that such attacks might be planned, but they were ignored or passive assistance was provided for these attacks to be successful.
The independent reviews that were conducted do not support these theories, however. There were independent bodies who conducted reviews after the disasters happened. For instance, the National Institute of Standards and Technology investigated the claims that were made by several conspiracy theorists regarding the 9/11 attacks. There were reviews done by the civil engineering experts that proved that jet aircraft that flew in at high speed had created the impact which in turn led to the demolition and fires that broke out. Hence, the collapse of the Twin Towers was reviewed and concluded to be a result of the impact created by the flown in airplanes. However, many are reluctant to believe that, US authorities at the highest level as well as the militia was ignorant of such forthcoming attacks. Hence, the possibilities that there was inside knowledge, but it was overlooked are hard to put aside. In the light of such views, it is ironical that the power games that higher authorities play results in the loss of millions of innocent lives of people who have no right to be made pawns in the hands of world political leaders who choose to play God.