The most prominent conspiracy theories can be broadly divided into three main forms:
- LIHOP (“Let it happen on purpose”) – suggests that key individuals within the government had at least some foreknowledge of the attacks and deliberately ignored it or actively weakened United States’ defenses to ensure the hijacked flights were not intercepted. Similar allegations were made about Pearl Harbor.
- MIHOP (“Make/Made it happen on purpose”) – that key individuals within the government planned the attacks and collaborated with, or framed, al-Qaeda in carrying them out. There is a range of opinions about how this might have been achieved.
- Others – who reject the accepted account of the September 11 attacks are not proposing specific theories, but try to demonstrate that the U.S. government’s account of the events is wrong. This, according to them, would lead to a general call for a new official investigation into the events of September 11, 2001. According to Jonathan Kay, managing editor for comment at the Canadian newspaper National Post and author of the Among the Truthers: A Journey Through America’s Growing Conspiracist Underground, “They feel their job is to show everybody that the official theory of 9/11 is wrong. And then, when everybody is convinced, then the population will rise up and demand a new investigation with government resources, and that investigation will tell us what actually happened.”
Conspiracy theorists claim that action or inaction by U.S. officials with foreknowledge was intended to ensure that the attacks took place successfully. For example, Michael Meacher, former British environment minister and member of Tony Blair’s government, said that the United States knowingly failed to prevent the attacks.
Suspected insider trading
Some conspiracy theorists maintain that just before 9/11, an “extraordinary” amount of put options were placed on United Airlines and American Airlines stocks and speculate that insiders may have known in advance of the coming events of 9/11 and placed their bets accordingly. An analysis into the possibility of insider trading on 9/11 concludes that:
A measure of abnormal long put volume was also examined and seen to be at abnormally high levels in the days leading up to the attacks. Consequently, the paper concludes that there is evidence of unusual option market activity in the days leading up to September 11 that is consistent with investors trading on advance knowledge of the attacks.
—Allen M. Poteshman, The Journal of Business
This study was intended to address the “great deal of speculation about whether option market activity indicated that the terrorists or their associates had traded in the days leading up to September 11 on advance knowledge of the impending attacks.”
In the days leading up to 9/11, analysis shows a rise in the put to call ratio for United Airlines and American Airlines, the two airlines from which planes were hijacked on 9/11. Between September 6 and 7, the Chicago Board Options Exchange recorded purchases of 4,744 “put” option contracts in UAL and 396 call options. On September 10, more trading in Chicago saw the purchase of 4,516 put options in American Airlines, the other airline involved in the hijackings, with a mere 748 call options in American purchased that day. No other airline companies has unusual put to call ratio in the days leading up to the attacks. The 9/11 Commission concluded that all these abnormal patterns in trading were coincidental.
Insurance companies saw anomalous trading activities as well. Citigroup Inc., which has estimated that its Travelers Insurance unit may pay $500 million in claims from the World Trade Center attack, had about 45 times the normal volume during three trading days before the attack for options that profit, if the stock falls below $40. Citigroup shares fell $1.25 in late trading to $38.09. Morgan Stanley, which occupied 22 floors at the World Trade Center, experienced bigger-than-normal pre-attack trading of options that profited when stock prices fell. Other companies directly affected by the tragedy had similar jumps.
Raytheon, a defense contractor, had an anomalously high number of call options trading on September 10. A Raytheon option that makes money, if shares are more than $25 each had 232 options contracts traded on the day before the attacks, almost six times the total number of trades that had occurred before that day.
The initial options were bought through at least two brokerage firms, including NFS, a subsidiary of Fidelity Investments, and TD Waterhouse. It was estimated that the trader or traders would have realized a five million dollar profit. The Securities and Exchange Commission launched an insider trading investigation in which Osama bin Laden was a suspect after receiving information from at least one Wall Street Firm.
The 9/11 Commission Report concluded that “Exhaustive investigations by the Securities and Exchange Commission, FBI, and other agencies have uncovered no evidence that anyone with advance knowledge of the attacks profited through securities transactions.” The report further stated:
Highly publicized allegations of insider trading in advance of 9/11 generally rest on reports of unusual pre-9/11 trading activity in companies whose stock plummeted after the attacks. Some unusual trading did in fact occur, but each such trade proved to have an innocuous explanation. For example, the volume of put options — investments that pay off only when a stock drops in price — surged in the parent companies of United Airlines on September 6 and American Airlines on September 10 — highly suspicious trading on its face. Yet, further investigation has revealed that the trading had no connection with 9/11. A single U.S.-based institutional investor with no conceivable ties to al Qaeda purchased 95 percent of the UAL puts on September 6 as part of a trading strategy that also included buying 115,000 shares of American on September 10. Similarly, much of the seemingly suspicious trading in American on September 10 was traced to a specific U.S.-based options trading newsletter, faxed to its subscribers on Sunday, September 9, which recommended these trades. These examples typify the evidence examined by the investigation. The SEC and the FBI, aided by other agencies and the securities industry, devoted enormous resources to investigating this issue, including securing the cooperation of many foreign governments. These investigators have found that the apparently suspicious consistently proved innocuous.
Air defense stand down theory
A common claim among conspiracy theorists is that the North American Aerospace Defense Command (NORAD) issued a stand down order or deliberately scrambled fighters late to allow the hijacked airplanes to reach their targets without interference. According to this theory, NORAD had the capability of locating and intercepting planes on 9/11, and its failure to do so indicates a government conspiracy to allow the attacks to occur. Conspiracy theorist Mark R. Elsis says: “There is only one explanation for this … Our Air Force was ordered to Stand Down on 9/11.”
One of the first actions taken by the hijackers on 9/11 was to turn off or disable each of the four aircraft’s on board transponders. Without these transponder signals to identify the airplane’s tail number, altitude, and speed, the hijacked airplanes would have been only blips among 4,500 other blips on NORAD’s radar screens, making them very difficult to track.
On 9/11, only 14 fighter jets were on alert in the contiguous 48 states. There was no automated method for the civilian air traffic controllers to alert NORAD. A passenger airline had not been hijacked in the U.S. since 1979. “They had to pick up the phone and literally dial us,” says Maj. Douglas Martin, public affairs officer for NORAD. Only one civilian plane—a chartered Learjet 35 with golfer Payne Stewart and five others on board—was intercepted by NORAD over North America in the decade prior to 9/11, which took one hour and 19 minutes.
Rules in effect at that time, and on 9/11, barred supersonic flight on intercepts. Before 9/11, all other NORAD interceptions were limited to offshore Air Defense Identification Zones (ADIZ). “Until 9/11 there was no domestic ADIZ,” says FAA spokesman Bill Schumann. After 9/11, the FAA and NORAD increased cooperation. They set up hotlines between command centers while NORAD increased its fighter coverage and installed radar to watch airspace over the continent.
The longest warning NORAD received of the hijackings was some eight minutes for American Airlines Flight 11, the first flight hijacked. The FAA alerted NORAD to the hijacked Flight 175 at just about the same time it was crashing into the World Trade Center’s South Tower. The FAA notified NORAD of the missing – not hijacked – Flight 77 three minutes before it struck the Pentagon. NORAD received no warning of the hijack of United Flight 93 until three minutes after it had crashed in Pennsylvania.
It has been claimed that Israeli agents may have had foreknowledge of the attacks. Four hours after the attack, the FBI arrested five Israelis who had been filming the smoking skyline from the roof of a white van in the parking lot of an apartment building, for “puzzling behavior.” The Israelis were videotaping the events, and one bystander said they acted in a suspicious manner: “They were like happy, you know… They didn’t look shocked to me. I thought it was very strange.” While The Forward, a New York Jewish news magazine, reported that the FBI concluded that two of the men were Israeli intelligence operatives, a spokesperson for the Israeli Embassy in the United States said that they had not been involved in any intelligence operation in the United States. The FBI eventually concluded that the five Israelis had no foreknowledge of the attacks.
World Trade Center
The plane crashes and resulting fires caused the collapse of the World Trade Center. Controlled demolition conspiracy theories say the collapse of the North Tower, South Tower, or of 7 World Trade Center was caused by explosives installed in the buildings in advance.
Demolition theory proponents, such as Brigham Young University physicist Steven E. Jones, architect Richard Gage, software engineer Jim Hoffman, and theologian David Ray Griffin, argue that the aircraft impacts and resulting fires could not have weakened the buildings sufficiently to initiate a catastrophic collapse, and that the buildings would not have collapsed completely, nor at the speeds that they did, without additional factors weakening the structures.
In the article “Active Thermotic Material Discovered in Dust from the 9/11 World Trade Center Catastrophe”, which appeared in the Open Chemical Physics Journal, authors Niels Harrit of the University of Copenhagen’s Department of Chemistry, Jeffrey Farrer of Brigham Young University’s Department of Physics and Astronomy, Steven E. Jones, and others state that thermite and nano-thermite composites in the dust and debris were found following the collapse of the three buildings. The article contained no scientific rebuttal and the editor in chief of the publication subsequently resigned.
Jones has not explained how the amount of explosive needed to bring down the buildings could have been positioned in the two buildings without drawing attention, but mentioned efforts to research the buildings’ maintenance activity in the weeks prior to the event. Federal investigators at the National Institute of Standards and Technology state that enormous quantities of thermite would have to be applied to the structural columns to damage them, but Jones disputed this, saying that he and others were investigating “superthermite”. Brent Blanchard, author of “A History of Explosive Demolition in America”, who corresponded with Jones, states that questions about the viability of Jones’ theories remain unanswered, such as the fact that no demolition personnel noticed any telltale signs of thermite during the eight months of debris removal following the towers’ collapse. Blanchard also said that a verifiable chain of possession needs to be established for the tested beams, which did not occur with the beams Jones tested, raising questions of whether the metal pieces tested could have been cut away from the debris pile with acetylene torches, shears, or other potentially contaminated equipment while on site, or exposed to trace amounts of thermite or other compounds while being handled, while in storage, or while being transferred from Ground Zero to memorial sites.
Jones also said that molten steel found in the rubble was evidence of explosives, as an ordinary airplane fire would not generate enough heat to produce this, citing photographs of red debris being removed by construction equipment, but Blanchard said that if there had been any molten steel in the rubble any excavation equipment encountering it would have been immediately damaged. Other sampling of the pulverized dust by United States Geological Survey and RJ Lee did not report any evidence of thermite or explosives. It has been theorized the “thermite material” found was primer paint. Dave Thomas of Skeptical Inquirer magazine, noting that the residue in question was claimed to be thermotic because of its iron oxide and aluminum composition, pointed out that these substances are found in many items common to the towers. Thomas said that in order to cut through a vertical steel beam, special high-temperature containment must be added to prevent the molten iron from dropping down, and that the thermite reaction is too slow for it to be practically used in building demolition. Thomas pointed out that when Jesse Ventura hired New Mexico Tech to conduct a demonstration showing nanothermite slicing through a large steel beam, the nanothermite produced copious flame and smoke but no damage to the beam, even though it was in a horizontal, and therefore optimal position.
The National Institute of Standards and Technology (NIST) concluded the accepted version was more than sufficient to explain the collapse of the buildings. NIST and many scientists refuse to debate conspiracy theorists because they feel it would give those theories unwarranted credibility. Specialists in structural mechanics and structural engineering accept the model of a fire-induced, gravity-driven collapse of the World Trade Center buildings without the use of explosives. As a result, NIST said that it did not perform any test for the residue of explosive compounds of any kind in the debris.
Soon after the day of the attacks, major media sources published that the towers had collapsed due to heat melting the steel. Knowledge that the burning temperatures of jet fuel would not melt the steel support structure of the WTC contributed to the belief among skeptics that the towers would not have collapsed without external interference (something other than the planes). NIST does not claim that the steel was melted, but rather that the weakened steel, together with the damage caused by the planes’ impacts, caused the collapses. NIST reported that a simulation model based on the assumption that combustible vapors burned immediately upon mixing with the incoming oxygen showed that “at any given location, the duration of [gas] temperatures near 1,000 °C was about 15 to 20 [minutes]. The rest of the time, the calculated temperatures were 500 °C or below.”
Since 9/11, at least two steel-framed high-rise buildings have collapsed following blazes — the Plasco Building in Tehran, Iran on January 19, 2017, and the Wilton Paes de Almeida Building in São Paulo, Brazil, on May 1, 2018.
Political activist Thierry Meyssan and filmmaker Dylan Avery claim that American Airlines Flight 77 did not crash into the Pentagon. Instead, they argue that the Pentagon was hit by a missile launched by elements from inside the U.S. government. Some claim that the holes in the Pentagon walls were far too small to have been made by a Boeing 757: “How does a plane 125 ft. wide and 155 ft. long fit into a hole which is only 60 ft. across?” Meyssan’s book, L’Effroyable Imposture (published in English as 9/11: The Big Lie) became available in more than a dozen languages. When released, the book was heavily criticized by both the mainstream French and American press, and later, from within the 9/11 Truth movement. The French newspaper Liberation called the book “a tissue of wild and irresponsible allegations, entirely without foundation.”
In response to the conspiracy theorists’ claim of a missile hitting the Pentagon, Mete Sozen, a professor of civil engineering at Purdue University argues that: “A crashing jet doesn’t punch a cartoon-like outline of itself into a reinforced concrete building. When Flight 77 hit the Pentagon, one wing hit the ground and the other was sheared off by the Pentagon’s load-bearing columns.” According to ArchitectureWeek, the reason the Pentagon took relatively little damage from the impact was because Wedge One had recently been renovated. (This was part of a renovation program which had been begun in the 1980s, and Wedge One was the first of five to be renovated.)
Evidence contradicting some conspiracy theorists’ claim of a missile hitting the Pentagon have been described by researchers within the 9/11 Truth Movement, such as Jim Hoffman, in his essay “The Pentagon Attack: What the Physical Evidence Shows”, and by others broadly refuting the role of other conspiracies in the attacks. The evidence refuting missile claims includes airplane debris including Flight 77’s black boxes, the nose cone, landing gear, an airplane tire, and an intact cockpit seat were observed at the crash site. The remains of passengers from Flight 77 were indeed found at the Pentagon crash site and their identities confirmed by DNA analysis. Many eyewitnesses saw the plane strike the Pentagon. Further, Flight 77 passengers made phone calls reporting that their airplane had been hijacked. For example, passenger Renee May called her mother to tell her that the plane had been hijacked and that the passengers had been herded to the back of the plane. Another passenger named Barbara Olson called her husband (U.S. Solicitor General Theodore Olson) and said that the flight had been hijacked, and that the hijackers had knives and box cutters. Some conspiracy theories say the phone calls the passengers made were fabricated by voice morphing, the passengers’ bodies disposed of, and a missile fired at the Pentagon.
The pressure group Judicial Watch filed a Freedom of Information Act request on December 15, 2004, to force the government to release video recordings from the Sheraton National Hotel, the Nexcomm/Citgo gas station, Pentagon security cameras and the Virginia Department of Transportation. On May 16, 2006, the government released the Pentagon security camera videos to Judicial Watch. The image of American Airlines Flight 77 which appears in the videos has been described as “[a] white blob” and “a white streak” (by the BBC), “a thin white blur” (by The Associated Press), and “a silver speck low to the ground” (in The Washington Post). A sequence of five frames from one of the videos already appeared in the media in 2002. Some conspiracy theorists believe the new video does not answer their questions.
The fourth plane hijacked on 9/11, United Airlines Flight 93, crashed in an open field near Shanksville, Pennsylvania, after the passengers revolted. Out of the four planes hijacked on that day, Flight 93 was the only one not to reach its target.
One of the popular conspiracy theories surrounding this event is that Flight 93 was actually shot down by a U.S. fighter jet. David Ray Griffin and Alex Jones say that large parts of the plane including the main body of the engine landed miles away from the main wreckage site, too far away for an ordinary plane crash. Jones says that planes usually leave a small debris field when they crash, and that this is not compatible with reports of wreckage found farther away from the main crash site. One person claimed that the main body of the engine was found miles away from the main wreckage site with damage comparable to that which a heat-seeking missile would do to an airliner.
According to some theories, the plane had to be shot down by the government because passengers had found out about the alleged plot.
According to Phil Molé of Skeptic magazine, “[this] claim rests largely on unsupported assertions that the main body of the engine and other large parts of the plane turned up miles from the main wreckage site, too far away to have resulted from an ordinary crash. This claim is incorrect, because the engine was found only 300 yards from the main crash site, and its location was consistent with the direction in which the plane had been traveling.” Michael K. Hynes, an airline accident expert who investigated the crash of TWA Flight 800 in 1996, says that, at very high velocities of 500 mph or more, it would only take a few seconds to move or tumble across the ground for 300 yards.
Reports of wreckage discovered at Indian Lake by local residents are accurate. CNN reported that investigators found debris from the crash at least eight miles away from the crash site, including in New Baltimore. However, according to CNN, this debris was all very light material that the wind would have easily blown away, and a Pittsburgh Post-Gazette article from September 14, 2001, describes the material as “mostly papers”, “strands of charred insulation”, and an “endorsed paycheck”. The same article quotes FBI agent Bill Crowley that, “Lighter, smaller debris probably shot into the air on the heat of a fireball that witnesses said shot several hundred feet into the air after the jetliner crashed. Then, it probably rode a wind that was blowing southeast at about 9 m.p.h.” Also, the distance between the crash site and Indian Lake was misreported in some accounts. According to the BBC, “In a straight line, Indian Lake is just over a mile from the crash site. The road between the two locations takes a roundabout route of 6.9 miles—accounting for the erroneous reports.”
Some conspiracy theorists believe a small white jet seen flying over the crash area may have fired a missile to shoot down Flight 93. However, government agencies such as the FBI assert this small plane was a Dassault Falcon business jet asked to descend to an altitude of around 1,500 ft to survey the impact. Ben Sliney, who was the FAA operation manager on September 11, 2001, says no military aircraft were near Flight 93.
Some internet videos, such as Loose Change, speculate that Flight 93 safely landed in Ohio, and a substituted plane was involved in the crash in Pennsylvania. Often cited is a preliminary news report that Flight 93 landed at a Cleveland airport; it was later learned that Delta Flight 1989 was the plane confused with Flight 93, and the report was retracted as inaccurate. Several websites within the 9/11 Truth Movement dispute this claim, citing the wreckage at the scene, eyewitness testimony, and the difficulty of secretly substituting one plane for another, and claim that such “hoax theories… appear calculated to alienate victims’ survivors and the larger public from the 9/11 truth movement”. The editor of the article has since written a rebuttal to the claims.
Valencia McClatchey, a local woman who took the only photograph of the mushroom cloud from the impact of Flight 93 seconds after it hit the ground, says she has been harassed over the telephone and in person by conspiracy theorists, who claim she faked the photo. The FBI, the Somerset County authorities, the Smithsonian, and the National Park Service’s Flight 93 National Memorial staff have all individually examined the photograph as well as the film negatives and all four agencies consider the photo to be authentic.
While some conspiracy theorists have claimed that passengers of Flight 93 and/or Flight 77 were murdered or that they were relocated, with the intent that they never be found, others within the 9/11 Truth Movement, such as Jim Hoffman and Scholars for 9/11 Truth & Justice, repudiate such claims.