Detectives already have been assigned to all of the dozens of high-rise hotels in the area, with the aim of preventing the type of attack that happened in Las Vegas in October, when a gunman firing from a casino hotel killed dozens of people at an outdoor concert below.
NY is set to step-up security ahead of the New Year's day festivities in Times Square.
Terrorist threats are ever present in places which are popular holiday destinations.
The annual New Year's Eve Ball Drop that will welcome 2018 is about to take place in Time Square.
To stop a suicide bomber from detonating an explosive like the one set off December 11 under the Port Authority bus terminal, police officers will search celebrants twice, once when approaching the Times Square area, then again at each pen - with dogs trained to sniff air off a person's body, by metal detectors and by officers who look through each person's bags.
There are other events going on throughout the city.
Those who will use their mobile phones to see over two million people welcome the new year can access the different mobile webcasts that are prepared for the event. That was the message from New York City Mayor Bill de Blasio, in the wake of an attempted pipe bomb attack earlier this month.
This, as NY officials estimate some six million visitors are spending holiday time in the city.
Monahan, the NYPD's patrol chief, said that beginning at 11 a.m. Sunday, crosstown traffic would be shut from 37th to 59th streets and Sixth to Eighth avenues, and the area will be sealed off with concrete barriers, blocker cars and sand trucks.
For spectators, there are only 12 access points. All small bags will be searched.
The line-up includes Mariah Carey, who is set to redeem herself from her highly-talked about performance previous year. As a public event at the Times Square, the New Year's festivities and ball drop are broadcast on television to be watched worldwide.
Now, law enforcement is gearing up for the city's famed New Year celebrations.
"The takeaway from our preparations is this: People will be safe, and they should feel safe, too", O'Neill said.