NEW YORK (CBSNewYork) — The NYPD on Monday mounted an exercise to test its response to terrorist attacks like those in Paris and Brussels – just as disturbing video surfaced of the Paris attackers partying in a nightclub just months before the carnage.

As CBS2 Political Reporter Marcia Kramer reported, the NYPD was trying to prepare itself Monday in the event of a terrorist attack – in which an active shooter is trying to kill as many people as possible, or in which a suicide bomber detonates explosives.

“The locations we chose today were all chosen for their iconic value,” said NYPD Chief of Department James O’Neill.

O’Neill said police do not have time to come up with a complex blueprint on the fly, WCBS 880’s Rich Lamb reported.

“There’s a plan that we have and we have to make sure that as people and these positions change, they know what their duties and responsibilities are and they’re very specific,” O’Neill said.

Meanwhile, the new video showed the Paris plotters partying and drinking in a Brussels club. Suspect Brahim Abdeslam was clearly visible with a cigarette in his hand as he flirted with a blonde girl, while his younger brother, Salah, was seen whooping it up in an orange sweatshirt.

CNN obtained the video from two friends of the terror suspects responsible for the Paris carnage back on Friday, Nov. 13, 2015.

The video was remarkable because it was just shot eight months before Brahim would blow himself up at a café in the 11th arrondissement of Paris. His suicide was part of a deadly ISIS mission that killed 130 people and injured hundreds more.

Salah Abdeslam survived, and was captured earlier this month after he fled to Brussels.

“Salah took care of himself. He was very neat; someone who was very funny; someone you could have a laugh with; a bit of a lady’s man,” one friend told CNN.

“Brahim was a lot more intelligent,” another friend said. “He was also better behaved.”

The video was an important lesson for the NYPD because it showed how quickly someone can be radicalized – and how little time it takes someone to morph from a hard partier to a terrorist killer, Kramer reported.

“It can happen that quickly,” said police Commissioner Bill Bratton.

Mayor Bill de Blasio, Bratton, and NYPD Deputy Chief of Intelligence and Counter-terrorism John Miller said the city hopes its attempts to improve relations with the Muslim community will provide intelligence about when people become radicalized.

Kramer asked the officials whether they are worried they might miss the signs if radicalization can happen so quickly.

“It’s always something we think about. As you have duly noted, the time from blast to bang; from radicalization to action, is something in the ISIS era we’ve seen shortened,” Miller said. “It is something that then underscores the need for greater community involvement.”

As 1010 WINS’ Al Jones reported, Miller noted that the NYPD drill on Monday happened the same day as police shot and wounded a man who allegedly pulled a gun on officers at the U.S. Capitol Visitor Center in Washington. Also Monday, a bomb-sniffing dog alerted its handler to something in Times Square.

“The whole process of dealing with multiple crises on paper in the tabletop while multiple crises were unfolding outside was part of the learning experience,” Miller said.

Miller said the dog’s warning in Times Square ended up being a false alarm.

After watching the tabletop counterterrorism exercise, Mayor de Blasio said the NYPD is ready to deal with any ISIS-inspired terrorist attack.