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New York - Although no specific plot has been identified, revelers this Fourth of July can expect extraordinary security -- from expanded patrols and SWAT units to biological weapon response teams and undercover officers mingling with celebratory crowds.
"It's absolutely not a joke," said New York police Sgt. Thomas Horvath, who took ABC News on patrol around New York City's waterways. "The threat is very real. On the day of the [July 4] event, we're going to put out basically every asset we have."
And those assets will likely include a boat designed for the NYPD that detects radiation from a nuclear bomb or radiological "dirty" bomb.
The Chicago Police Department says they will have an "elevated presence throughout the downtown area and other critical locations throyghout the weekend" including both uniformed and "cover" officers.
Its sophisticated equipment monitors all radiation readings in the area. Any suspicious readings can be instantly sent to the Brookhaven laboratory in Washington D.C. for analysis by nuclear physicists. There are only two such boats in the world.
This year, police are especially concerned because evidence from Osama bin Laden's compound revealed that he wanted to kill Americans on July Fourth or by the 10th anniversary of Sept. 11.
"We all know that the Fourth of July is a signature holiday," Los Angeles Police Chief Charlie Beck said Friday. "Some of our enemies abroad would like to exploit that."