Bagpipes and drums sounded across Ground Zero today as the US marked the eighth anniversary of the September 11 attacks in ceremonies led for the first time by US President Barack Obama.
In New York, the melancholy music mingled with rain as the crowd of mourners, police, firefighters, servicemen and officials, including Vice President Joseph Biden, gathered at the annual ceremony.
Amid driving rain, Obama led a moment of silence at the White House at 8:46 am (1246 GMT), the instant the first of four planes, piloted by Al-Qaeda hijackers, slammed into the north tower of New York's World Trade Center.
"Let us renew our resolve against those who perpetrated this barbaric act and who plot against us still," Obama said at a later ceremony at the Pentagon military headquarters, which was also hit by a plane.
About 3,000 people died, including 2,752 in New York, on September 11, 2001, in the attacks which demolished both towers of the World Trade Center, and crashed into the Pentagon outside Washington, and a Pennsylvania field.
The attacks triggered then president George W. Bush's controversial invasions of Iraq and Afghanistan and a "war on terror" that Obama has inherited and is struggling to manage.
For a few hours, the increasingly rancorous debate over the mounting casualties and the military strategy was set aside as the country unified around the simple and moving ceremonies in New York and Washington.
Moments of silence were observed in New York to mark the impacts of each plane and the collapse of each tower, while the names of every victim were read out.
Mayor Michael Bloomberg said the day should also be remembered for the many who volunteered to help in the aftermath of the attack, including the 343 firefighters killed responding to the catastrophe.
"Their compassion and selfless acts are etched in our city's history," Bloomberg said.
As every year, relatives of the dead and other volunteers took turns to read the names of the dead in a ritual carried live on local television.
Many choked back tears as they went through the litany against a background of somber violin, guitar and flute music.
"This is not the rain, I'm sorry. This is tears," one man said, clutching a photograph of his lost relative, the rainy weather so different from that crisp, autumn day eight years ago.
At nightfall, powerful lights were to send two beams skyward from Ground Zero, which eight years later remains a vast hole, with only the first elements of foundations in place for new towers.
In a sign of how jittery the nation remains after the worst ever attack on its soil, a Coast Guard training exercise Friday on the Potomac River opposite the Pentagon triggered an immediate scare and anger.
The Coast Guard said it would review what happened, but added the best way to remember September 11 "is to be always ready and this requires constant training and exercise."
Obama meanwhile wrote in a letter published on the front page of the New York Daily News that "we are all New Yorkers," saying the attacks "will be forever seared in the consciousness of our nation."
"We will never forget the images of planes vanishing into buildings; of billowing smoke rolling down the streets of Manhattan; of photos hung by the families of the missing," Obama wrote.
But he also reminded increasingly skeptical Americans that US troops were in Afghanistan because the country had been the principal base for Al Qaeda prior to 9/11. The war there, he said, was meant "to take the fight to the extremists who attacked us."
The memorial at Ground Zero remains mired in building delays, while one planned for Shanksville, Pennsylvania, has been held up by political and design disagreements.
Shanksville is the site where United Airlines Flight 93 crashed in an open field after passengers overwhelmed the hijackers, who are speculated to have been aiming the plane for the Capitol building in nearby Washington.
Meanwhile, prayer services and interfaith remembrances were scheduled throughout the day, with a candlelight "peace vigil" closing out the commemorations.
One US cable news network, MSNBC, marked the anniversary by replaying the terrifying minute-by-minute video of the first moments of the attacks when planes hit the world Trade Center.