Sept. 11, 2001

An American flag flies over the rubble of the collapsed World Trade Center towers following the Sept. 11, 2001 terror attacks on New York and Washington.

That day, 10 years ago, made al Qaeda a feared and hated name in households across the United States.

The group, led by Osama bin Laden and at that time clearly based along the mountainous border shared by Pakistan and Afghanistan, enjoyed it's greatest success on Sept. 11, but it wouldn't be the last.

The coming decade would see al Qaeda adapt in deadly fashion to a much more overtly hostile environment, by changing tactics and locations. But as this collection of photos shows, their core philosophy of attacking civilians to instill fear has changed very little.

Credit: AP Photo/Beth A. Keiser

Shoe Bomber

With the horror of Sept. 11 still fresh in the minds of the American public, there came another scare from the sky.

On December 22, 2001, self-confessed al Qaeda member Richard Reid boarded a Paris to Miami flight with a home-made bomb concealed in his shoe. He tried to blow up the jet but failed to light the fuse before being subdued by passengers and the flight crew.

Reid was convicted of all charges against him and is currently serving a life sentence at a Colorado prison.

Credit: AP

Execution of Daniel Pearl

Daniel Pearl, an Asia editor for The Wall Street Journal, traveled from his home in India to neighboring Pakistan in early 2002 to investigate Richard Reid's connections to al Qaeda.

On Jan. 23, he got in a taxi and headed to what he thought was an interview with a prominent Muslim cleric. It was a trap, and he found himself the captive of an al Qaeda cell in Karachi.

Credit: AP

Execution of Daniel Pearl

Daniel Pearl was held for more than a week by the militants and then beheaded - allegedly by Khaled Sheikh Mohammed, one of the architects of the Sept. 11 attacks.

His body was found, beheaded and mutilated, in a shallow grave outside Karachi. Pakistan's links to militant Islamic groups became an increasing topic of discussion in the corridors of power in Washington.

Adam Daniel Pearl was born in Paris less than three months after his father's remains were found.

Credit: AP

Bali Night Club Bombings

In October 2002, bombs tore through popular tourist hangouts on the Indonesian island of Bali, leaving more than 200 people dead and showing that al Qaeda's influence in Asia spread far beyond Afghanistan and Pakistan.

Credit: AP

Bali Night Club Bombings

The al Qaeda-linked Jemaah Islamiyah group was behind the double-bomb attack on nightclubs in Bali's trendy Kuta neighborhood. A third device caused just minor damage near a U.S. consular office.

Indonesia is the world's most populous Muslim nation, and the U.S. has increased it's cooperation with the government and military to try and tackle extremist groups.

Credit: AP

Bali Night Club Bombings

Imam Samudra, one of the accused masterminds of the Bali bombings, was executed in Indonesia along with two other men for their roles in the attacks.

Riduan Isamuddin, aka "Hambali", suspected of involvement in the plot, is currently in U.S. custody, but has not been charged with any crimes.

Credit: AP

Istanbul Bombings

This photo shows the aftermath of a bomb blast at the HSBC bank building, in Istanbul, Turkey, on Nov. 20, 2003. It was one of two truck-bombs that rattled the Turkish capital as then-President George W. Bush visited the Muslim-majority U.S. ally.

Turkish Muslim separatist groups claimed responsibility for the attacks, including bombings five days earlier which killed 27 people near synagogues in the capital city.

Turkey's government, however, dismissed those claims, saying the domestic groups could not have amassed the resources to carry such a dramatic attack to fruition.

In total, 57 people were killed in the two days of bloodshed.

Credit: AP

Istanbul Bombings

Turkish officials blamed al Qaeda for the attacks, suggesting the nation's secular society and friendly relations with the U.S. and other Western nations was the likely motivation.

Two of the primary suspects in the attacks, Habib Aktas and Azad Ekinci, reportedly met Osama bin Laden's top lieutenant, Ayman al-Zawahiri, several times prior to the bombings.

"They were the only ones to meet with al-Zawahiri," another suspect told police during questioning. "The instructions came from him. They would meet (with him) at least three times a year, using false identity documents."

Credit: AP

July 7/7 Attacks, London

On July 7, 2005, four young Muslim men, who had lives and families in England, where they had lived for years, carried bombs onto London's Underground trains and one bus during morning rush hour.

This security camera image shows them arriving at Luton railway station north of London at 7:21 a.m.

Credit: AP

July 7/7 Attacks, London

Three of the men, two of Pakistani origin and one of Jamaican, blew themselves up on packed trains at exactly 8:50 a.m. The fourth detonated his device at 9:47 a.m. on a bus, seen here, in London's Tavistock Square.

It was the first incident to highlight the threat from al Qaeda-inspired "homegrown" terrorists in Europe.

In a video testimony made before he blew himself up, the eldest of the bombers, 30 year old Mohammad Sidique Khan, praised Osama bin Laden and other al Qaeda leaders as "today's heroes."

Credit: AP

July 7/7 Attacks, London

The 52 innocent commuters killed in the London bombings are commemorated by 52 stainless steel columns which now stand as a memorial in Hyde Park.

Among the bombers belongings, investigators found copies of speeches by Anwar al-Awlaki, an extremist Muslim preacher who would later become one of the key figures in al Qaeda's Yemen-based branch - now seen as one of the greatest threats to America and its allies.

Credit: AP Photo/Fiona Hanson/PA

Marriott Hotel Bombing

In September 2008, al Qaeda and its allies saw a chance to bring terror back onto their home turf - and to try and kill a number of American soldiers in the process.

At left, destruction caused by a bomb at the Marriott hotel in Islamabad, Pakistan. A huge suicide truck bomb devastated the heavily guarded hotel and left more than 50 people dead.

The building was engulfed in flames in a stark reminder to Pakistan's leaders that cooperation with the U.S.-led war on terror would be met with revenge.

Credit: AP Photo/Anjum Naveed

Marriott Hotel Bombing

In this photo a security guard helps a foreign guest out of the Marriott after the bomb blast.

About 30 U.S. Marines were reportedly staying at the hotel when the blast struck - possibly the intended targets of the bomb.

American officials have said al Qaeda's operations chief in Pakistan, who was killed in a subsequent drone strike, was behind the attack.

Credit: AP Photo/Rizwan Khan

Ft. Hood Massacre

On Nov. 5, 2009, Maj. Nidal Hasan, an Army psychiatrist and American-born Muslim who was to deploy to Afghanistan the following month, walked into a medical building at the Army's Ft. Hood in Texas and opened fire.

He killed 13 of his fellow soldiers and left more than two dozen more wounded.

Ft. Hood Massacre

Hasan was a homegrown, "lone-wolf" style terrorist - but he did not become a radicalized in a vacuum.

The FBI discovered multiple, direct communications between Hasan and the Yemeni cleric, Anwar al-Awlaki. The domestic spy agency was later slammed in a Senate report - along with the Army itself - for failing to detect the threat lurking in the Army's own quarters.

Hasan will be tried in a military court and face the death penalty if convicted, the commanding general for the Texas military post announced in July 2011.

Credit: AP Photo

Times Square Bomb Plot

On May 1, 2010, two alert street vendors saw a Nissan Pathfinder with smoke coming out of it parked near Times Square in Manhattan. They told police, and the bomb squad was able to disarm the explosives-packed car bomb before it did any harm.

The FBI built and blew up a mock-up of the device to show that, had it detonated as planned on the crowded road in Times Square, the toll in human lives could have been significant.

Credit: CBS

Times Square Bomb Plot

Faisal Shahzad, a 30-year-old American citizen of Pakistani descent, was pulled off a flight several days later as he tried to flee to Dubai. He admitted building the device and lighting the fuse himself. It was just luck that his skills as a bomb builder were insufficient.

The former budget analyst from Connecticut received $15,000 for his plot and about five days of training from the Pakistani Taliban

Credit: AP/U.S. Marshals Service

Delta Flight 253

Umar Farouk Abdulmutallab, the son of a wealthy Nigerian businessman, would be the next of al-Awlaki's disciples to become a household name in the U.S.

In this image from an al Qaeda video obtained by ABC News, Abdulmutallab receives training at a desert camp in Yemen.

Credit: AP/ABC News

Delta Flight 253

"There is no doubt that he was in contact with al Qaeda in Shabwa province," Rashad al Alimi, Yemen's deputy prime minister said in 2010. "Maybe with Anwar al-Awlaki."

Abdulmutallab worked largely independently after his training and indoctrination in Yemen, planning to down a commercial airliner over a large U.S. city.

He later told investigators al-Awlaki directed him to carry out the attack on an airliner.

Credit: CBS/AP

Delta Flight 253

Here, remnants of the "underwear bomb" allegedly carried by Abdulmutallab aboard Delta Flight 253 to Detroit, on Christmas day, 2010.

Abdulmutallab ultimately failed. His device failed to detonate and he was taken into custody, where he eventually turned against al-Awlaki and provided U.S. authorities with intelligence on al Qaeda in the Arabian Peninsula.

Again, the U.S. intelligence community was taken to task for missing myriad clues which signaled Abdulmutallab's intent to attack the United States - from intercepted phone calls referring to "the Nigerian," to a warning from his own father at the U.S. Embassy in Nigeria, to the fact he boarded a flight to Detroit in December with no baggage and no coat.

In the wake of the Ft. Hood attack and Abdulmutallab's arrest, many saw a shift in al Qaeda's strategy - a preference for smaller, harder to detect operations.

Credit: FBI

Cargo Bomb Plot

Al Qaeda's next attempt to blow up commercial aircraft over the United States also failed in its ultimate goal, but it did highlight a serious weakness in modern aviation security.

The glaring shortcomings of the cargo shipping system were laid bare when al Qaeda in the Arabian Peninsula - the Yemen-based branch - managed to get two viable bombs onto FedEx and UPS jets headed for U.S. airspace.

Credit: AP Photo

Cargo Bomb Plot

The devices, which U.S. authorities say were likely assembled by AQAP's top bomb builder in Yemen, were sophisticated - hidden within the components of computer printers, and slipped easily into cargo shipping containers.

Those containers were placed aboard both cargo and passenger jets en route to the U.S. before a tip from Saudi Arabia's intelligence services led to their discovery on Oct. 29, 2010 at airports in Britain and Dubai.

Credit: Dubai Police/ENA

Cargo Bomb Plot

The cargo bombs were rendered safe, and in the end caused no harm - only momentary panic.

Unlike the dramatic changes in passenger air travel seen after 9/11, little or no change has been implemented in cargo screening, and there's broad consensus that it remains an Achilles heal in aviation security.

The devices were also a reminder that Anwar al-Awlaki, and al Qaeda in the Arabian Peninsula, represent a very real and growing threat to the U.S. homeland - a threat capable of evolving in response to changing security practices.

Credit: AP/Dubai Police

Al Qaeda in Iraq

Al Qaeda had no significant presence in Iraq prior to the 2003 U.S. war to topple Saddam Hussein's regime. But as American troops poured in, and images of death and destruction filled the Muslim world's airways and websites, that changed.

Al Qaeda in Iraq was born, and it is hard to overstate the satellite group's devastating toll on post-Saddam Iraq.

In this Aug. 15, 2011 photo, Iraqi security forces inspect the site where a suicide car bomber plowed his vehicle into a checkpoint outside a police building just outside the holy city of Najaf.

Credit: AP Photo/Alaa al-Marjani

It is impossible to pin a precise death toll on al Qaeda in Iraq, due to the sheer number of attacks which plagued the country for years following the U.S. invasion and the fact that they were carried out by a range of insurgent and Islamic fundamentalist groups.

However, the independent "Iraq Body Count" project says 12,284 Iraqis were killed by suicide attacks between 2003 and 2010. Suicide bombing is a tactic favored more by al Qaeda than other Muslim militant groups.

In this photo an Iraqi man cries as he walks away from the destroyed ministries of justice and labor, following a suicide bomb attack on Oct. 25, 2009. The attack in central Baghdad left some 90 people dead.

Credit: AHMAD AL-RUBAYE/AFP/Getty Images