Biden, Obama, Clinton and Bush all take part in ceremonies marking 20 years since devastating terrorist plane attacks on World Trade Center and Pentagon

Herzog recalls horror of attacks, salutes first responders; other world leaders offer messages of solidarity to Washington, saying attackers failed to destroy Western values

In video message to commemorate the nearly 3,000 people killed by Al-Qaeda, Biden urges Americans to show unity, calling it 'our greatest strength'

Efraim Halevy was meeting the PM when the news came in: 'Sharon told me something has happened. You should be in your office'

Mass terror attacks in 2001 led to increased emphasis on security, which Jewish Federations of North America chief says 'is now the cost of doing business in the Jewish world'

'We must stay ahead of emerging security threats,' says aviation official, noting measures taken in past 20 years to help prevent further attacks

Play tells story of 7,000 passengers, including a rabbi, who were rerouted to small Canadian town amid the horror of the attacks, and the warm welcome they received from locals

Volunteer fire warden Alan Fromm rushed into 5 World Trade Center to evacuate his office building; after the South Tower collapsed, he was found unconscious under an ambulance

Warned that 'there is an aircraft coming at you,' staffers were urged to kick off their shoes and flee, but they quickly found ways to keep on working

20 years after the country was used as a staging base for the 9/11 attacks, Lloyd Austin says the Taliban is 'on notice' that the US expects it to keep al-Qaeda quashed in Kabul