A small army of security forces, shuttered Metro stops, re-routed buses -- Washington will leave nothing to chance next week to protect leaders at President Barack Obama's nuclear security summit.
The 47-nation summit, the most vast international gathering the US capital has seen in decades, will draw on security know-how and manpower on a staggering scale and place parts of the capital on lockdown, officials said.
"The level of security needed... is immense," said Washington Mayor Adrian Fenty, noting that the city is no stranger to "big events" like presidential funerals or visits by the Dalai Lama, the Pope, or Britain's Queen Elizabeth.
But this gathering is "without any question one of the biggest, most prestigious important meetings that has ever taken place not just in this city but anywhere in the world," he said.
Motorcades zooming to and from the White House or the State Department are nothing new to Washington, blockaded streets come and go with events like World Bank or IMF meetings, but even jaded citizens may be in for some headaches.
"Be patient with us. This is Washington DC, we do a lot of big events here. It's a world class city and I think we do them very well," said the city's police chief, Cathy Lanier.
Each world leader is expected to bring their security detail, but the Obama's US Secret Service bodyguards are overseeing the overall effort to keep visiting dignitaries safe starting today.
"There will be different layers of security that will include a variety of different things visible and not visible," said Lanier, who declined to give precise numbers of agents deployed "for security reasons."
There will be parking bans, bus lines will deviate from their daily routes, some Metro stops will be closed, and police are expected to set up checkpoints in a three-block radius around the city's convention center.
"That is some burden. However, there is nothing more important that making sure that people who visit the country specially the leaders of 46 nations, do so in a safe and secured way as humanly possible," said Fenty.
Washington's airspace, already tightly controlled since the September 11, 2001 terrorist strikes, will buzz with security helicopters hovering overhead, while Coast Guard vessels will patrol the Potomac and other nearby waterways.
The gathering is "one of the biggest summits of its kind anywhere in the history of the world, outside of United Nations," said the mayor, who noted that Obama's January 2009 inauguration had packed the city with excited crowds.