20 years since 9/11: Defining images from two decades of the 'war on terror'

The second tower of the World Trade Center explodes into flames after being hit by an airplane in New York, Semore

President George W. Bush listens as White House Chief of Staff Andrew Card informs him of a second plane hittimore

A New York City fireman calls for more rescue workers to make their way into the rubble of the World Trade Cenmore

Investigators head into the debris field at the site of a commercial plane crash near Shanksville, Pennsylvanimore

The damaged area of the Pentagon building, where a commercial jetliner slammed into it September 11, is seen imore

Then-President George W. Bush is shown with retired firefighter Bob Beckwith (R) at the scene of the World Tramore

A US Air Force B-52 flies over after releasing its bombs on front line Taliban positions near Bagram airport, more

Anti-Taliban Afghan fighters watch several explosions from U.S. bombings in the Tora Bora mountains in Afghanimore

A young Afghan woman shows her face in public for the first time after 5 years of Taliban Sharia law as she wamore

A group of U.S. Marines of the 15th MEU (Marine Expeditionary Unity) move out to take a position in the desertmore

U.S. Marines from Charlie 1/1 of the 15th MEU (Marine Expeditionary Unit) fill sand bags around their light momore

The body of CIA officer Johnny Mike Spann is carried by a Marine honor guard from an Air Force aircraft at Andmore

U.S. Marines, shown through a night vision scope, escort battlefield detainees into a detention center at the more

An Afghan girl reads from the board in a home-based school in Kabul, December 2, 2001. The school, operating smore

U.S. Army 10th Mountain Division soldier Jorge Avino from Miami, Florida carves the body count their mortar temore

British soldiers serving with ISAF forces (International Security Assistance Force) in Kabul surround a beaconmore

More than 500 Sailors and Marines assemble on the flight deck of the USS Belleau Wood to commemorate the one-ymore

U.S. President George W. Bush addresses U.S. Army soldiers and their families at Fort Hood, Texas, January 3, more

An explosion rocks Baghdad during air strikes unleashed by U.S.-led forces, March 21, 2003. REUTERS/Gormore

U.S. Navy Hospital Corpsman HM1 Richard Barnett, 41, a medic with the 1st Marine Division, 1st Regimental Combmore

U.S. Marine Corp Assaultman Kirk Dalrymple watches as a statue of Iraq's President Saddam Hussein falls in cenmore

A British army officer holds her handgun cocked as Iraqi civilians flee fighting in Basra, Iraq, April 6, 2003more

Corporal Clifford Thompson from Clebourne, Texas, of HHC 4th Infantry Divsion of the U.S. Army looks through tmore

An Iraqi girl sits outside as U.S. soldiers of 720 Military Police Battalion of the Fourth Division search hermore

Iraqis celebrate on a downed U.S. Apache military helicopter in the Hindiya district, southwest of Baghdad, Mamore

A row of U.S. Army helmets are perched on M-16 rifles during a memorial at Al Asad air base for the 15 victimsmore

A detained Iraqi man with a plastic bag covering his head sits in garden of a house searched by U.S. soldiers more

U.S. Marines kick in a door while securing a building next to the main hospital in central Baghdad, which willmore

An Iraqi man suspected of having explosives in his car is held after being arrested by the U.S Army near Baqubmore

U.S. President George W. Bush delivers a speech to crew aboard the aircraft carrier USS Abraham Lincoln, as thmore

A U.S. Army soldier speaks with a comrade as they drive to a military hospital following a grenade attack in Bmore

An Iraqi girl holds her hands up while U.S. and Iraqi soldiers search her family house in Baquba, June 30, 200more

An Iraqi man holds the body of a boy after a car bomb explosion at a market in the neighborhood known as New Bmore

An Iraqi bystander lies dead in a pool of blood, killed by U.S. soldiers who opened fire following a rocket-prmore

Saddam Hussein is filmed after his capture in footage released December 14, 2003. REUTERS/Handout

Under a sign jokingly charging $100 per visit, Sgt Ramirez Ricardo, a soldier with the Fourth Infantry divisiomore

An Iraqi detainee gestures toward U.S. soldiers through the bars of his cell at Abu Ghraib prison outside Baghmore

An Iraqi youth stalks a U.S. Army Abrams tank in the Baghdad suburb of Abu Ghraib, April 8, 2004. REUTERS/Ali more

A Spanish police officer stands next to a victim as he looks out of the door of a train which was bombed outsimore

Mays, a young Iraqi Shi'ite girl, cries after a mortar shell which landed outside the family's home in a Najafmore

A British soldier jumps from a burning tank which was set ablaze after a shooting incident in the southern Iramore

A bloodied insurgent sits blindfolded in an Iraqi police station after being captured during a morning battle more

British Prime Minister Tony Blair stands on the steps in Gleneagles, Scotland, after hearing the news of the emore

The number 30 double-decker bus in Tavistock Square in central London after a bombing attack of four blasts thmore

Kristin Kenny of Edison New Jersey clutches the grave stone of her boyfriend Dennis Flanagan at Arlington Natimore

A photo reviewed by U.S. military officials shows detainees reading the Koran inside the grounds of the mediummore

A man runs down a street warning people to flee shortly after a twin car bomb attack at Shorja market in Baghdmore

A wounded Canadian soldier from the NATO-led coalition crawls for cover seconds after his position was hit by more

A U.S. soldier with 2nd Platoon, G Company, 3rd Squadron 2nd Striker Cavalry Regiment is reflected in a mirrormore

An Iraqi man holds the body of a boy after a car bomb explosion at a market in the neighborhood known as New Bmore

U.S. soldiers push the car of an Iraqi man to start the engine at a check point in north Baghdad, June 13, 200more

An Iraqi man unbuttons his shirt as U.S. soldiers point their laser sights on him during an operation near themore

Sgt. William Olas Bee, a U.S. Marine from the 24th Marine Expeditionary Unit, has a close call after Taliban fmore

A U.S. Army cadet reads a book entitled "Kill Bin Laden" as he waits with other cadets for President Barack Obmore

U.S. SPC Henry Rosenquist of 2-12 Infantry 4BCT-4ID Task Force Mountain Warrior sits in the computer room in Hmore

Afghan children look at Canadian soldiers of the NATO-led coalition while they patrol in their compound in themore

Laura Youngblood, widow of U.S. Navy Petty Officer Travis L. Youngblood, touches his gravestone in Section 60 more

A U.S. soldier of 2-12 Infantry 4BCT-4ID Task Force Mountain Warrior takes a break during a night mission nearmore

A U.S. Army medevac crew member attempts to revive a Marine mortally wounded in an IED blast near the town of more

A young girl stands with other mourners as the hearses carrying the coffins of five British soldiers are drivemore

U.S. Marine Lance Corporal Chris Sanderson, 24, from Flemington, New Jersey shouts as he tries to protect an Amore

U.S. Army soldiers from the 2nd Platoon, B battery 2-8 field artillery, fire a howitzer artillery piece at Sepmore

U.S. President Barack Obama and Vice President Joe Biden, along with members of the national security team, remore

The compound, within which al Qaeda leader Osama bin Laden was killed, is seen in flames after it was attackedmore

Revelers cheer outside the White House in Washington after President Barack Obama announced live on televisionmore

A plane flies through the "Tribute in Lights" in Lower Manhattan in New York ahead of the tenth anniversary ofmore

U.S. Air Force Major Stacie Shafran carries her luggage to a loading paddock while waiting for her departure fmore

U.S. Mine Resistant Ambush Protected (MRAP) vehicles drive through Camp Adder before departing what is now knomore

Boot prints of U.S. soldiers are seen at the nearly deserted Camp Adder, now known as Imam Ali Base, near Nasimore

Vehicles belonging to forces loyal to Libyan leader Muammar Gaddafi explode after an airstrike by coalition fomore

A protester reacts as the U.S. Consulate in Benghazi is seen in flames, September 11, 2012. REUTERS/Esam Al-more

Lesleigh Coyer, 25, of Saginaw, Michigan, lies down in front of the grave of her brother, Ryan Coyer, who servmore

A U.S. Army soldier with Charlie Company, 36th Infantry Regiment, 1st Armored Division blows a bubble with hismore

An explosion is seen during a car bomb attack at a Shi'ite political organization's rally in Baghdad, April 25more

U.S. troops from the Nato-led International Security Assistance Force (ISAF) light candles during Christmas Evmore

Militant Islamic State fighters take part in a military parade along the streets of northern Raqqa province inmore

A female member of the Kurdish People's Protection Units (YPG) mourns over the grave of her fellow fighter, whmore

Smoke rises over the Syrian town of Kobani after a U.S.-led airstrike, as seen from the Mursitpinar border cromore

Members of the Iraqi Special Operations Forces take their positions during clashes with the al Qaeda-linked Ismore

Displaced people from the minority Yazidi sect, fleeing violence from forces loyal to the Islamic State in Sinmore

French fire brigade members aid an injured individual near the Bataclan concert hall following fatal shootingsmore

Islamic State militants lead what are said to be Ethiopian Christians along a beach in Wilayat Barqa, in this more

A body is seen on the ground after 86 people were killed in Nice, France, when a truck ran into a crowd celebrmore

A man cries as he carries his daughter while walking from an Islamic State-controlled part of Mosul towards Irmore

An Iraqi special forces soldier shot dead an Islamic State suicide bomber in Mosul, Iraq, March 3, 2017. REUmore

A Syrian Democratic Forces (SDF) fighter sits as medics treat his comrades injured by sniper fire from Islamicmore

A member of the Syrian Democratic Forces calls his comrades during fighting with Islamic State fighters in Raqmore

A boy waits with his mother as they queue with others for humanitarian and medical help after leaving Baghouz,more

A convoy of U.S. vehicles is seen after withdrawing from northern Syria, in Erbil, Iraq, October 21, 2019. more

A baby is handed over to U.S. soldiers over the perimeter wall of the airport for it to be evacuated, in Kabulmore

A U.S. Air Force aircrew prepare for qualified evacuees to board a U.S. Air Force C-17 Globemaster III aircrafmore

Evacuees crowd the interior of a U.S. Air Force C-17 Globemaster III transport aircraft, carrying some 640 Afgmore

U.S. President Joe Biden salutes during the dignified transfer of the remains of military service members who more

Carrying his rifle down by his side, Major General Chris Donahue, commander of the storied 82nd Airborne Divismore

An American flag and red rose stand in the names of those lost at the edge of the south reflecting pool of themore