The security plan for the center, still seen as a terror target even as skyscrapers are being rebuilt, will be implemented in phases; eventually, more than 650 officers will be assigned to the area.
The World Trade Center has been attacked twice, once in 1993 and again on Sept. 11, 2001, and a plot was disrupted in 2006 to bomb a train tunnel and retaining wall at ground zero.
"We cannot dismiss the level of threat against this site, which remains squarely in the terrorists' crosshairs," Kelly said in a speech to the nonprofit Police Foundation.
The World Trade Center command will police the 16-acre site where five towers, a memorial, a transit hub and an arts center are envisioned, along with the area around the site, though block-by-block parameters haven't been established. The command will work with Manhattan precincts and the Port Authority of New York and New Jersey, which owns the site.
The total number of officers will make it larger than any other precinct, and police assigned to the command will have additional training, Kelly said. He has named a deputy inspector, who is currently working on plans for the memorial opening ceremony, for the new command.
A few officers already are working out of a police building in the area, but a new location will be found as the command increases in size, Kelly said.
The Port Authority and the New York Police Department sketched out a security agreement in 2008 that settled a dispute over who would watch over the area. The site is intertwined through underground utility infrastructure, as well as a vehicle security center - the main entrance to the underground parking and delivery areas at the trade center complex - train tracks and streets that would connect the office towers and the memorial.
The Port Authority will have primary responsibility for security at the PATH train station connecting lower Manhattan and New Jersey and will oversee the installation and maintenance of all security equipment at the World Trade Center.
It's not clear yet where the officers will come from - if they'll be transferred from other commands or more will be hired.
The NYPD, the nation's largest police department, is down thousands of officers from a high of more than 40,000 after Sept. 11.