Americans are marking the fourth anniversary of the September 11th terrorist attacks with somber memorials to the nearly 3000 people who were killed.
In New York, thousands have gathered at the former site of the World Trade Center, where most of the casualties occurred. Many people brought photographs of friends and relatives who were killed, and cried as speakers read out the names of the dead.
In New York and elsewhere, moments of silence were observed at the times when each of the four planes hijacked by al-Qaida terrorists crashed.
At the White House, President Bush and Vice President Dick Cheney led the first such moment at 8:46 am1246 universal time, the time the first of two planes hit the World Trade Center.
Other ceremonies took place in Arlington, Virginia, where a jetliner hit the Pentagon, and in Shanksville, Pennsylvania, where a fourth hijacked plane crashed into a field.
Speaking at the Pentagon ceremony, Defense Secretary Donald Rumsfeld vowed the United States will win the war on terror.