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12 Questions People Still Have About 9/11

Many Americans believe we'll never know everything there is to know about the 9/11 attacks. Here are some of the questions that still remain even 18 years later.

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A blimp flying over Manhattan, New York
Joseph Sohm/Shutterstock

How did the towers collapse so quickly?

The theory: Engineers designed the Twin Towers to withstand the impact of a commercial jet airplane. Yet, both towers collapsed within two hours of being hit. Could the towers have been rigged with explosives (demolition-style) prior to the planes hitting?

The consensus: Snopes discredited this as not scientifically sound, and the world may never know how these optimally-engineered towers collapsed so quickly. All of these conspiracy theories actually turned out to be true.

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Aluminum recycling

Did the aircraft materials contribute?

The theory: The primary material used in constructing airplanes is aluminum. According to the Smithsonian channel, two scientists have independently pointed out that at extremely high temperatures (over 1,000°F), aluminum melts and becomes a powerful explosive when it comes into contact with water. They theorize the burning towers formed a “furnace” of sorts, melting the aluminum, which would have then exploded on contact with water from the building’s sprinklers.

The consensus: This is one explanation that could account for the towers’ “demolition-style” collapse. Read the story of the woman that was personally blamed for the terrorist attacks on 9/11.

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Library Card Catalog Drawer Magnifier Glass Search Concept Stock Photo

Why no mention of the aluminum in the official report?

The theory: The Smithsonian points out that the official investigation report doesn’t even mention the presence of aircraft wreckage in the towers. Why?

The consensus: It’s possible investigators failed to recognize the material as aluminum in its molten state or for some other reason considered it not important. These are the strangest unsolved mysteries from each state.

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Hacker using laptop. Lots of digits on the computer screen.

Why did the government ignore the warning the day before?

The theory: The day before the 9/11 attacks, the U.S. government’s National Security Agency (NSA) intercepted two communications, both from Afghanistan to Saudi Arabia. One says, “Tomorrow is zero hour.” The other says, “The match begins tomorrow.” These messages were not translated until September 12, according to CNN. Was there a reason for this?

The consensus: This remains a mystery. Here are 16 more of history’s strangest unsolved mysteries.

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12 Secrets They're Still Not Telling You About 9/11

Where was the NSA on September 10, 2001?

The theory: Assuming the NSA didn’t translate these ominous messages on the day they were intercepted, there’s still the question of what the agency was doing that day.

The consensus: The CIA had been on high alert since August 23 that a terrorist attack by Al Qaeda was imminent. Check out these secret U.S. Government operations, revealed.

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How early did the government know?

The theory: As early as July 31, 2001, the FAA had issued a warning to airlines that “terror groups are known to be planning and training for hijackings.” And according to CNN, this wasn’t the first such warning issued by the government.

The consensus: In fact, it may have been even earlier. As far back as 1998, the FAA had been warning airlines and airports to maintain a “high degree of alertness” in response to ominous statements made by Osama bin Laden. These are the things the Government doesn’t want you to know about Area 51.

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Video camera in focus, blurred spokesman in background

Why didn’t anyone warn us?

The theory: On August 6, 2001, the CIA reported to President George W. Bush that al Qaeda was planning airline hijackings, according to CNN. This information was passed on to embassies and other overseas organization. But not the American public. Was there a good reason for this? There’s a chance that authorities didn’t take the threat seriously, and there’s a chance that they believed there was little citizens could have done to alter the outcome.

The consensus: Most people—especially families of the victims—would have preferred that the American public had a warning.

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Close up of business woman handing smartphone.
Jaktana phongphuek/Shutterstock

Will this change the way governments handle alerts?

The theory: It should. Last June, the European Union enacted legislation requiring that citizens be alerted to potential terrorist attacks. The legislation has been called “lifesaving.”

The consensus: Post-9/11 our country has made its own sweeping changes. U.S. agencies have been more forthcoming about potential danger. Homeland Security’s color-coded system (red being the highest threat) has been replaced by the National Terrorism Advisory system, which keeps us posted with “elevated” and “imminent” alerts. In addition, all major cellular companies also have the capability of warning subscribers about threat level changes. Finally, ground zero is home to a new tower. Learn how 1 World Trade Center was built to be safer than the Twin Towers.

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12 Secrets They're Still Not Telling You About 9/11
Mark Van Scyoc/Shutterstock

Why won’t anyone tell the FBI what happened?

The theory: The greatest enduring conspiracy theory regarding the 9/11 attacks is why the CIA blocked communications that would have informed the FBI of impending terrorist attacks. “It’s horrible. We still don’t know what happened,” Newsweek quotes one of the FBI’s lead counterterrorism agents as saying.

The consensus: For some former national security officials, this question alone rivals even those we ponder regarding the assassination of U.S. President John F. Kennedy.

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Memorial at Ground Zero Manhattan for September 11 Terrorist Attack with an American Flag Standing near the Names of Victims Engraved
Minghong Xia/Shutterstock

Could the attacks have been prevented?

The theory: The CIA blocked information regarding a possible attack in both 2000 and 2001 from reaching the FBI. “It is patently evident the attacks did not need to happen and there has been no justice,” Mark Rossini, one of two FBI agents assigned to the CIA’s Osama bin Laden unit, told Newsweek.

The consensus: Many family members of 9/11 victims would agree. This woman survived 9/11—these are the questions she gets asked the most.

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Saudi Arabia flag waving on the wind
IZZ HAZEL/Shutterstock

What was the Saudi Arabian government’s involvement?

The theory: In the 2018 book, The Watchdogs Didn’t Bark: The CIA, NSA, and the Crimes of the War on Terror, authors Ray Nowosielski and John Duffy theorized a conspiracy between the U.S. government and the Saudi Arabian government to cover up the true events of 9/11. Newsweek said the authors make a compelling case.

The consensus: As we’re still asking ourselves these questions 18 years later, the world may never have closure about the tragic events of that day. Don’t miss the 13 powerful things that surviving 9/11 taught this woman.

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12 Secrets They're Still Not Telling You About 9/11

Could it happen again?

The theory: Perhaps the most sensitive question that remains 18 years after the attacks of September 11, 2001, is whether it could happen again. Many airport security and other measures have been taken to prevent plane hijackings, so it’s unlikely it could happen again.

The consensus: The greater risk is that we may all start to feel too “safe”; according to this report by ABC News: “The greatest vulnerability in the security system may be complacency—that government officials, airlines, and passengers will let their guard down.” Next, read about these simple twists of fate that saved these people’s lives on 9/11.


  • Snopes: Did a European Scientific Journal Conclude 9/11 Was a Controlled Demolition?
  • Smithsonian Channel: How Aluminum May Have Collapsed the Twin Towers
  • CNN: September 11 Warning Signs Fast Facts
  • Newsweek: CIA and Saudi Arabia Conspired to Keep 9/11 Details Secret, New Book Says
  • ABC News: Could Sept. 11 Happen Again?

Lauren Cahn
Lauren Cahn is a New York–based writer whose work has appeared regularly on Reader's Digest and in a variety of other publications since 2008. She covers life and style, popular culture, law, religion, health, fitness, yoga, entertaining and entertainment. Lauren is also an author of crime fiction, and her first full-length manuscript, "The Trust Game," was short-listed for the 2017 CLUE Award for emerging talent in the genre of suspense fiction.