Updated

Thousands of police will swarm New York's subways, sidewalks and airspace on what officials promised would be the city's most heavily guarded New Year's Eve ever.

Some security measures — counter-snipers on rooftops, metal detectors on street corners — are becoming as much a part of New Year's in New York as party hats and confetti.

But with the nation on orange alert, there will be more officers on duty this year than last, and they will focus more heavily on hotels, landmarks and ferry terminals, police Commissioner Ray Kelly (search) said Tuesday. He wouldn't reveal the number of officers.

Police are focusing on hotels and other "soft targets" as a result of intelligence and counterterror units' analyses of anti-American "chatter" gathered from the Internet and other sources, Kelly said.

"We think it's prudent for us to do that," he said.

City officials often say New York has been on the equivalent of orange alert since Sept. 11, 2001. But hikes in national terrorism preparedness nearly always lead to additional security measures in New York, too.

That's because threats to the city are often a large part of the reason why the national threat level is raised, said Pat Damuro, assistant director in charge of the FBI's New York office.

The office will have four times as many agents on duty in its 24-hour operations center, along with hundreds of other agents on duty or standing by, Damuro said.

Some will be in Times Square (search). Others will be in squads that can be quickly deployed to chase down leads in case of an imminent attack, Damuro said.

"We've pulled out all the stops," he said.

The police department will have seven helicopters above the Times Square crowd, including a new $9.8 million model packed with communications equipment and cameras for scanning crowds.

Organizers said they expect this year's crowd to be larger than last year's mass of 750,000.

Manhole covers are being sealed shut in Times Square, and mail boxes, trash cans and newspaper boxes are being removed. Plainclothes officers will mingle with the crowds, and elite counterterror teams will have equipment to detect chemical, biological or radiological contamination.

"Sadly," Mayor Michael Bloomberg (search) said, "terrorism is something that we have to live with. Leave the worrying to the professionals."