Six years after the September 11 attacks on New York and Washington, Americans are planning a series of toned-down ceremonies on Tuesday to remember the nearly 3,000 people who lost their lives.
For the first time since the attacks, there was to be no ceremony at the site where the World Trade Centre towers once stood, though family members would be allowed a brief visit to lay flowers and wreaths down to what is now a construction pit at Ground Zero.
President George W Bush is to participate in a moment of silence on the White House lawn at 8.46 a.m. (12.46 GMT), the minute the first hijacked plane slammed into the north tower of the New York landmark, also on a Tuesday. Church bells will toll in New York to mark the time of the impacts.
On Monday, Bush attended a memorial service in Somerset, Pennsylvania for the victims of United Flight 93, which crashed in a field in nearby Shanksville as passengers apparently succeeded in preventing the hijackers from reaching their target.
Instead of Ground Zero, a nearby park has been chosen this year for the New York ceremony, where family members and local politicians will read the names of the city's more than 2,700 victims. Mayor Michael Bloomberg and former mayor Rudi Giuliani - currently running for the Republican presidential nomination - are expected to attend. Giuliani's role has been reduced from past years in an effort by families not to politicise the occasion.