US Marks 25 Years Since the Sept 11 Attacks

The milestone anniversary brought memorial rituals — wreath-laying, flag-flying, moments of silence, vigils and readings of victims' names — and volunteer projects in tribute to a day that about half of U.S. adults remember as the most historic event of their lifetime, according to a new poll.

On Sept. 11, 2001, al-Qaida extremists hijacked four commercial jets and crashed them into New York's World Trade Center, the Pentagon and a field near Shanksville, Pennsylvania.

The impacts brought down the World Trade Center's twin towers and blew a hole in the Pentagon, the U.S. military's fortress like headquarters near Washington. The fourth plane also was headed for the nation's capital, officials concluded, but the aircraft went down in Pennsylvania after passengers and crew members stormed the cockpit and fought the hijackers.

The U.S.-led global war on terrorism included invasions of Iraq and Afghanistan — the latter Washington’s longest war — and detentions and harsh interrogation of terror suspects in an international network of secret CIA prisons. The U.S. military found and killed al-Qaida leader Osama bin Laden in Pakistan in 2011, but accused 9/11 mastermind Khalid Sheikh Mohammed still awaits a trial 23 years after his capture.