WASHINGTON DC is going into lockdown today for the presidential inauguration of Barack Obama, the biggest single-day security operation the world has ever seen.
With crowds of up to four million predicted and most of the world tuning in, a 3.5sq mile area of the city will be sealed off, with entry possible only via airport-style metal detectors.
Further security cordons extend in concentric rings out from the Capitol building, with all bridges sealed off within an even larger area. Some 50,000 security personnel from 58 services will flood the city, in an operation costing $80 million (£55 million).
"It will be the most security, as far as I'm aware, that any inauguration's had," the homeland security chief, Michael Chertoff, said.
Drawing on the experience of the 2005 London Tube bombings, when the bombers used outlying stations as staging points, 1,000 plainclothes FBI officers in 155 teams will mingle with crowds at subway stations across Washington, hoping to spot would-be terrorists.
At the tip of the security spear are the so-called "Men in Black", a 100-strong unit of snipers from the Secret Service.
Armed with a customised weapon, the snipers are able to hit a target the size of a saucer at 1,000 yards.
From early this morning, they will be deployed in teams of two on rooftops along Pennsylvania Avenue to watch over the presidential motorcade.
When one of the team spots a threat, the other trains his rifle on the target while the spotter takes the role of "wind caller", advising on corrections for wind based on flags and chimney smoke – one reason the Secret Service says the more flags on display the better.
Pictures from Washington's 5,265 surveillance cameras will be fed into a central security command centre.
More than 8,000 state and federal police are in the city, with attention centred on the 1.9-mile Mall, where more than a million will gather to watch the swearing-in on giant TV screens.
An additional 10,000 part-time National Guard troops will be deployed, with 20,000 in reserve, along with an undisclosed number of regular troops.
Hoteliers, meanwhile, have received training on how to spot a terrorist threat, with the authorities mindful that the Mumbai attackers in November singled out hotels as "soft" targets.
Chemical, biological and radiological detectors, installed after 9/11, are already in place, and public buildings will be closed.
Coast Guard craft will patrol the Potomac river, and F-16 fighters will roam the skies, with all civil air traffic banned. "I think we are ready," Mr Chertoff said. "Part of my job is to hope for the best and plan for the worst."
For today, the "worst" includes not just the risk of a terrorist attack, but managing huge crowds and guarding against stampedes or injury during and after the noon ceremony.
Much of the security effort is focused on the internet, with unprecedented attention being paid both to al-Qaeda cyber traffic and messages sent by so-called white supremacists.
In August, a group of white neo-Nazis with sniper rifles were arrested at the Democratic Party's Denver convention.
The only public airing of neo-Nazi views has been the declaration by the National Knights, a faction of the Ku Klux Klan, that they will wear black armbands and display the US flag upside down to protest at the inauguration of the first mixed-race president.
'We should learn from King's vision'THE president-elect yesterday brought a whole new level of interest to "watching paint dry".
Barack Obama helped paint a wall at a shelter for homeless teenagers in south-east Washington, an area marred by poverty and deprivation, to mark the public holiday celebrating the birth of the assassinated civil rights icon Martin Luther King.
The shelter provides training for the youngsters and places an emphasis on self-reliance, a virtue that Mr Obama extolled during his election campaign.
"Dr Martin Luther King's was a life lived in loving service to others," said Mr Obama, who, in earlier years, worked in similar projects for the unemployed of Chicago's South Side. "His was a vision that all Americans might share the freedom to make of our lives what we will."
He appealed to the nation to remember King through service to others.
"As we honour that legacy, it's not a day just to pause and reflect – it's a day to act," he said.
"I ask the American people to turn today's efforts into an ongoing commitment to enriching the lives of others in their communities, their cities and their country."
Live blog (2-6pm GMT): The inauguration of Barack Obama