9/11 Terrorist Attacks – Key Vocabulary

These vocabulary flashcards cover the main figures, events, tactics, and security issues discussed in the lecture on the 9/11 terrorist attacks.

9/11 (September 11, 2001)

Coordinated terrorist attacks in which four hijacked U.S. commercial airplanes were used against the World Trade Center, the Pentagon, and an intended target in Washington, D.C.

Osama bin Laden

Saudi-born founder of al-Qaeda who orchestrated the 9/11 attacks and declared a holy war against the United States.

al-Qaeda

Militant Islamist organization formed by Osama bin Laden that planned and executed the 9/11 attacks.

Soviet Invasion of Afghanistan (1979-1989)

Conflict that drew together U.S., Saudi, and Islamist fighters (including bin Laden) against Soviet forces, setting the stage for future radicalization.

Mujahideen

Islamist rebel groups who fought the Soviets in Afghanistan, backed by the U.S., U.K., and Saudi Arabia.

Gulf War (1990-1991)

Conflict in which U.S. troops were stationed in Saudi Arabia—an action that angered bin Laden and fueled his anti-U.S. stance.

Holy War (Jihad) against the U.S.

Religious declaration by al-Qaeda to combat American political and military influence in the Islamic world.

Kamikaze-style Airplane Attack

Tactic of crashing fuel-laden commercial jets to create massive explosions and structural damage, used on 9/11.

World Trade Center Twin Towers

Iconic New York City skyscrapers destroyed when two hijacked Boeing 767s were flown into them on 9/11.

Pentagon

U.S. Department of Defense headquarters in Virginia struck by a hijacked Boeing 757 on 9/11.

U.S. Capitol (Intended Target)

Symbol of American political power believed to be the destination of United Airlines Flight 93 before passengers revolted.

Boeing 767

Wide-body jet model used by hijackers to hit the North and South Towers of the World Trade Center.

Boeing 757

Narrow-body jet model used to strike the Pentagon and the plane that crashed in Pennsylvania after passengers fought back.

Muscle Hijackers

Fifteen al-Qaeda operatives trained to subdue crews and passengers while four pilot-hijackers flew the planes.

Box Cutters

Small blades legally allowed on pre-9/11 flights; used by hijackers to threaten crew and gain cockpit access.

Pre-9/11 Airport Security

Minimal screening consisting mainly of basic metal detectors that permitted knives under four inches, enabling the hijackers’ weapons to pass.

Cockpit Door Keys

Physical keys held by flight attendants that opened pre-9/11 cockpit doors, exploited by hijackers to seize control.

Reinforced Cockpit Doors

Post-9/11 security upgrade making cockpit doors bullet- and blast-resistant and kept locked during flight.

Five-Year Preparation (1996-2001)

Period in which al-Qaeda recruited operatives, trained pilots, and finalized the 9/11 plot.

Flight 93 Passenger Revolt

Action by passengers that thwarted hijackers, causing the plane to crash in Pennsylvania instead of hitting its Washington target.

Saudi Citizenship Revocation

Punishment imposed on bin Laden in the 1990s for criticizing Saudi-U.S. relations, leading to his exile in Sudan and Afghanistan.

Symbolic Targets

Structures like the World Trade Center, Pentagon, and Capitol chosen by al-Qaeda to undermine U.S. economic and military power