This September marks the 15th anniversary of the 9/11 terrorist attacks on the United States.
There are some however who do not believe the official story of events, shrouding the day in a fog of suspicion and doubt. Whilst some theories push the limits of belief casting blame on shape-shifting aliens or asking us to consider whether the planes were in fact 'missiles surrounded by holograms made to look like planes', other theories do raise a few eyebrows. Here, we take a look at the five most compelling theories:
1. The Twin Towers were brought down by explosives not planes
Within just a few hours of the attacks on the Twin Towers, perhaps the most well-known of all the theories had already surfaced in an Internet chat room. The author of that post likened the collapse of the North and South Towers to an act of controlled demolition due to the way the buildings fell so quickly and perfectly into their own footprint. After the dust had settled, theorists raised further evidence in the form of witness testimonies, citing reports of explosions being heard before the Towers collapsed and debris visibly shooting out from the lower levels of the buildings.
When the official report stated the Towers fell due to severe structural damage caused by the planes and resulting fires, conspiracy theorists or 'truthers' as they are otherwise known, argued the fires did not burn for long enough (56 minutes in the case of the South Tower) to cause the catastrophic collapses.
2. A missile hit the Pentagon (not American Airlines Flight 77)
Early video footage and photos taken from the scene did not seem to show much evidence of plane wreckage. Theorists maintain this was evidence that the Pentagon was not struck by Flight 77, but by a missile or unmanned drone instead. They also argue that the structural damage to the building was too minor to have been made by a commercial airliner and question why the plane (piloted by an amateur) was even allowed to crash into the headquarters of the United States Department of Defense.
3. United Airlines Flight 93 was shot down
According to official reports, the passengers onboard Flight 93 attempted to take back the plane from the hijackers and the subsequent struggle caused the aircraft to crash into an open field in Pennsylvania. As with the Pentagon attack, theorists state that little plane wreckage was actually discovered in the field and the crash site itself was too small for an airliner that size, arguing instead that the plane was shot down by the military and so it disintegrated over a larger area.
4. The United States government knew about the attacks and stood the military down
A common belief amongst 'truthers' is that the North American Aerospace Defense Command (NORAD) deliberately ordered their fighter jets to stand down and allow the hijacked planes to reach their targets. America seemingly had the most powerful air force in the world but failed to intercept any of the planes that day, which theorists believe is an indication of a government conspiracy to let the attacks go ahead. Why would they do such a thing? Conspiracy theorists believe that the government wanted to use the attacks to justify an invasion on Iraq and Afghanistan to secure oil interests.
5. Insider traders knew about the attacks
In the days preceding the attacks, an 'extraordinary' amount of put options (investments that pay off only when a stock drops in price) were placed on the stocks of two airlines – American and United, which happened to be the airlines hijacked during 9/11. As such, some theorists believe that traders had been given advance warning of the attacks and were cashing in on the tragedy.