On the morning of Tuesday, Sept. 11, 2001, four U.S. airliners were turned into guided missiles after they were hijacked by al-Qaeda suicide bombers and crashed into three sites in the U.S., killing approximately 3,000 people.

Two of the planes struck the twin towers of the World Trade Center in New York, igniting fires that destroyed the 110-storey landmarks, while a third crashed into the west wing of the Pentagon in Washington. A fourth plane, which was believed to be heading for the White House, crashed in a field 120 kilometres southeast of Pittsburgh.

Names used by the hijackers, some of whom learned to fly at American pilot schools:

American Airlines Flight 11
Crashed into New York City's World Trade Center North Tower at 8.48 a.m.

• Mohamed Atta
• Satam al-Suqami
• Waleed M. Alshehri
• Wail M. Alshahri
• Abdulaziz Alomari

United Airlines Flight 175
Crashed into New York City's World Trade Center South Tower at 9.03 a.m.

• Marwan Al-Shehhi
• Ahmed Alghamdi
• Hamza Alghamdi
• Mohald Alshehri
• Fayez Rashid Ahmed Hassan al-Qadi Banihammad

American Airlines Flight 77
Crashed into the Pentagon at 9.39 a.m.

• Khalid Almihdhar
• Majed Moqed
• Nawaf Alhazmi
• Salem Alhamzi
• Hani Hanjour

United Airlines Flight 93
Crashed in a Pennsylvania field at 10.10 a.m.

• Saeed Alghamdi
• Ahmed Alnami
• Ziad Samir al-Jarrah
• Ahmed Ibrahim al-Haznawi

Masterminded by al-Qaeda

Not long after the attacks, officials in the U.S. identified Pakistan-born Khalid Sheik Mohammed as the senior al-Qaeda strategist who orchestrated the plot. He had been previously implicated in a 1995 plot known as Operation Bojinka, an early version of the Sept. 11 assault concept, that was broken up by police in the Philippines before it could be carried out. Mohammed was captured in 2003.

A rude Awakening

The attacks forced a new reality on the Western world, and on Americans in particular.

In the ensuing years, particularly before a formal U.S. inquiry known as the 9/11 Commission, evidence emerged that American authorities had received warnings about imminent attacks in the months leading up to Sept. 11, both from their own intelligence agencies and at least four foreign governments.

Determined not to be caught off guard again, the Bush administration dramatically reorganized its intelligence operations. It expanded unilateral presidential powers; set up a Department of Homeland Security that would introduce drastic changes to travel requirements and tighten airport and border security; and launched a wide-ranging "war on terror" that saw U.S. troops invade Afghanistan and oust the Taliban government, which had played host to al-Qaeda founder Osama bin Laden and his senior lieutenants.

In the spring of 2003, the war on terror led to the invasion of Iraq after the U.S. accused its dictator, Saddam Hussein, of creating weapons of mass destruction. American forces toppled Saddam, but none of those weapons were ever found. The fighting in Iraq triggered a series of upheavals, many along Muslim sectarian lines, in the Middle East and turned the entire region into an international hot spot.

Five years later

Five years after the attack, and despite America's overwhelming military might, bin Laden remains at large and the American-led coalition in Iraq has become bogged down in an unpopular war. Close to 3,000 U.S. soldiers have been killed in Iraq and confidence in the Bush presidency has plunged.

Canada stayed out of the Iraq war, a decision taken by the Liberal government of the day. However, to assist in the war on terror, Canadian forces have taken the lead role in Afghanistan, where they have engaged in a series of bloody encounters with remnants of the fundamentalist Taliban army.

So far, Canada has been spared any direct attacks but the country has not been immune to terror's threat: In June 2006, police charged 17 people, most of them young and of South Asian descent, with plotting to blow up landmarks in Toronto and Ottawa.