With streets blocked off and police blimps flying overhead, rifle-toting National Guardsmen striding through Grand Central Terminal and radiation detectors in place, this city all but bristles with security and anti-terrorist armament.

Police have doubled the number of undercover officers riding the buses and subways, and video cameras provide 24-hour feeds from bridges and tunnels. The federal government has cleared a seven-mile-radius airspace "frozen zone" over Madison Square Garden -- site of the Republican National Convention -- and a high-tech, 2,000-square-foot nerve center at police headquarters will hold representatives from 66 federal, state and city law enforcement agencies. [...]

New York may have never been so well guarded. But some New Yorkers find the buildup to the GOP convention unsettling. In interviews, several dozen spoke of the disruptions caused by the phalanxes of police and National Guard troops, by protesters bent on civil disobedience, and by the roving security details assigned to Republican VIPs. Many residents, particularly immigrants, worry that they will spend a week as suspects in their city.

"People are afraid now," said Mohammad Razvi, an auxiliary police officer and executive director of a respected community group that serves Pakistani and Bangladeshi immigrants. "Whenever these terror warnings go up, they are like: 'Oh, no, are they going to pick on us again?' "