The rise of new
conspiracy movements online, such as QAnon, whose followers, among other
conspiratorial views, believe a US "deep state" responsible for the attacks,
has kept these conspiracy theories in circulation and brought them to a far
And online clips from a series of films known as Loose Change have
reinforced many of the falsehoods circulating.
Some claim the US government staged the attacks or knew of them in advance
and allowed them.
And these falsehoods mesh with more recent online movements' belief global
elites plan to curtail civil liberties in response to the attacks and
facilitate the establishment of an authoritarian world government.
A claim widely shared online, "Jet fuel cannot melt steel beams," suggests
the World Trade Center's Twin Towers were demolished by explosives.
Additionally, the fires reached up to 1,000C in some areas, causing the
steel beams to warp and the eventual collapse of the buildings.
The collapse of 7 World Trade Center, a 47-storey skyscraper in the vicinity
of the Twin Towers, has attracted many conspiracy theories, some of which
were trending on major social networks on last year's 9/11 anniversary.
This building - containing offices of the CIA, the Department of Defense,
and the Office of Emergency Management - collapsed hours after the Twin
Towers without being hit by a plane or directly targeted.
The fact the collapse of 7 World Trade Center was announced in a live report
by BBC News correspondent Jane Stanley - while it was still visibly standing
behind her - has been cited by conspiracy theorists as evidence major media
organisations were part of the inside-job plot.
The Reuters news agency had mistakenly reported the collapse of the
building, which was also picked up by CNN, just before the live report.
Reuters later issued a correction - but clips of the report continue go
viral in the days leading up to 9/11 anniversaries.
Some online conspiracy theories suggest US missiles were fired at the
Pentagon, as part of a government plot, and the hole left in the building
was too small to have been caused by a passenger plane.
But a member of the American Society of Civil Engineers told Popular
Mechanics magazine the
size and shape of the hole was due to one wing of the Boeing 757 hitting
the ground and the other being severed on impact with the building.
Meanwhile, United Airlines Flight 93 crashed near Shanksville, Pennsylvania,
after passengers tried to take control of the plane from the hijackers.
Online theories claim it was shot down by a white business jet flying into a
Believers conclude the Israeli government mounted the attacks to goad the US
into attacking its regional enemies or responsibility lies with powerful
Jewish elites who control world events from the shadows.
But of the 2,071 victims of 9/11 who worked at the World Trade Center, 119
were confirmed to be Jewish and at least a further 72 were believed to be
That would constitute
9.2% of the victims, according to research by BBC documentary Conspiracy
Files, broadly in line with the 9.7% of New York's commuting population
believed to be Jewish at the time.
And some estimate up to 400 Jewish people might have died that day.
Similar theories surround other states, including Iraq and Iran, but no
evidence of their direct involvement has ever been found.