Thousands of extra police officers and military troops are being brought in from around the country, and measures to protect against chemical and biological attack will be in place, along with decontamination tents.
At least 150 multiagency "intel teams" will deploy throughout the region so that undercover FBI agents and other behavior analysis specialists can look for trouble. Of particular interest: individuals or small groups of men with backpacks lurking in large crowds, or entering the Metro from distant suburban stations -- a pattern similar to the deadly attacks in London's subways in 2005.
In some areas, Washington will look like an occupied city. Sharpshooters will be on virtually every building. Law enforcement and intelligence nerve centers and mobile command posts are sprouting. The FBI is deploying a scary-looking armored assault vehicle and a weapons-of-mass-destruction response truck.
The military, supporting civilian authorities, is using sophisticated surveillance systems developed for the Iraq and Afghanistan wars to monitor the Mall. A P-3 Reconnaissance plane will fly above the Mall to collect information that can instantaneously be transmitted to the ground in the event of a threat. The high-tech system is known as "Rover."
The Pentagon also will station cameras and other detectors on buildings around the Mall on Inauguration Day to ensure a constant picture, Defense officials said.
Officials familiar with the military surveillance efforts say they will be able to do much more than watch the crowd. They can sense radiation associated with a dirty bomb and in some cases detect a conventional explosive device.
In addition to response, officials have worked on prevention. Authorities have been scouring the Internet and other extremist gathering places to look for signs of trouble. So far, they say, they aren't seeing any.
Domestically, white supremacists have discussed Obama in threatening terms since early in his candidacy. Threats increased after Obama won the Democratic primary and again after he won the election.
Obama has been a lightning rod not only because of his race, but due to what extremists believe to be his ties to Islam, perceived sympathy for Israel and even support for gun control measures.
But in recent weeks, the threatening "chatter" has died down, according to law enforcement officials and the Southern Poverty Law Center, which is active in tracking U.S.-based extremist activity.
