September 11 attacks

"9/11" redirects here. For other uses, see 911 and September 11 attacks (disambiguation).

 * *Top row:* The Twin Towers of the

World Trade Center burning
* *2nd row, left to right:* Collapsed section of

the Pentagon; Flight 175 crashes into 2 WTC
* *3rd row, left to right:* A firefighter requests

assistance at World Trade Center site;
Ground Zero; An engine
from Flight 93 is recovered
* *Bottom row:* Flight 77's collision with the

Pentagon as captured by three
 Location
* Arlington County, Virginia, U.S.;
 Date
 Target
* The Pentagon (AA 77)
 Attack type
* Suicide attacks
* Mass murder
 Deaths
 Injured
 No. of participants

The **September 11 attacks** (also referred to as **9/11**)[a] were a series of four coordinated terrorist attacks by the Islamic terrorist group al-Qaeda[3][4][5] against the United States on the morning of Tuesday, September 11, 2001. The attacks resulted in 2,977 fatalities, over 25,000 injuries, and caused at least $10 billion in infrastructure and property damage.[6][7] Additional people have died of dust-related cancer and respiratory diseases in the months and years following the attacks.

Four passenger airliners operated by two major U.S. passenger air carriers (United Airlines and American Airlines)—all of which departed from airports in the northeastern United States bound for San Francisco and Los Angeles—were hijacked by 19 al-Qaeda terrorists. Two of the planes, American Airlines Flight 11 and United Airlines Flight 175, crashed into the North and South towers, respectively, the World Trade Center complex in Lower Manhattan. Within an hour and 42 minutes, both 110-story towers collapsed. Debris and the resulting fires caused a partial or complete collapse of all other buildings in the World Trade Center complex, including the 47-story 7 World Trade Center tower, as well as significant damage to ten other large surrounding structures. A third plane, American Airlines Flight 77, was crashed into the Pentagon (the headquarters of the U.S. Department of Defense) in Arlington County, Virginia, which led to a partial collapse of the building's west side. The fourth plane, United Airlines Flight 93, was initially flown toward Washington, D.C., but crashed into a field in Stonycreek Township near Shanksville, Pennsylvania, after its passengers thwarted the hijackers. 9/11 is the single deadliest terrorist attack in human history and the single deadliest incident for firefighters and law enforcement officers in the history of the United States, with 343 and 72 killed, respectively.[8]

Suspicion quickly fell onto al-Qaeda. The United States responded by launching the War on Terror and invading Afghanistan to depose the Taliban, which had failed to comply with U.S. demands to expel al-Qaeda from Afghanistan and extradite their leader Osama bin Laden. Many countries strengthened their anti-terrorism legislation and expanded the powers of law enforcement and intelligence agencies to prevent terrorist attacks. Although bin Laden initially denied any involvement, in 2004 he claimed responsibility for the attacks.[2] Al-Qaeda and bin Laden cited U.S. support of Israel, the presence of U.S. troops in Saudi Arabia, and sanctions against Iraq as motives. After evading capture for almost a decade, bin Laden was located in Pakistan and killed by SEAL Team Six of the U.S. Navy in May 2011, during the Obama administration.

The destruction of the World Trade Center and nearby infrastructure seriously harmed the economy of New York City and had a significant effect on global markets. Wall Street was closed until September 17, and the U.S. and Canadian civilian airspaces until September 13. Many closings, evacuations, and cancellations followed, out of respect or fear of further attacks. Cleanup of the World Trade Center site was completed in May 2002, and the Pentagon was repaired within a year. The construction of One World Trade Center began in November 2006, and the building opened in November 2014.[9][10] Numerous memorials have been constructed, including the National September 11 Memorial & Museum in New York City, the Pentagon Memorial in Arlington County, Virginia, and the Flight 93 National Memorial at the crash site near Shanksville.

Based on the contents of 28 redacted pages of the 2002 Joint Inquiry into Intelligence Community Activities before and after the Terrorist Attacks of September 11, 2001, two former U.S. senators have alleged that the Saudi Arabian government was involved in the attacks.[11] These pages contain information regarding the material and financial assistance given by Saudi officials to the hijackers and their affiliates in advance of the attacks.[12]

As a consequence of the attacks, the United States has been in a state of national emergency ever since 2001.[13]