In New York's Times Square, there are visible signs that the city's anti terror squad is on the job. It's a job that gets harder and harder, guessing where terrorists could strike next.
Vincent Marra was a high ranking counter terrorism officer for the New York Police Department in the years following the 9/11 attacks. He says what happened in Paris is a sign of what could come.
"In this situation, the way they targeted young people. Late evening hours -- they knew what they were doing, they targeted people who were very susceptible, people who were out partying," Marra replied. "It's something that really hits home."
Marra believes this is just the latest tactic of ISIS terrorists.
"It looks to be terrorism evolving. It looks to be the next generation," he said.
Focusing primarily on what the experts call soft targets.
"The goal of hitting soft targets is to hit a place where's there's a lot of people -- to kill as many people as you could," Marra explained.
So what's the attraction of going for a café or a shopping mall?
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"In my opinion, it's an easy target and it's something that upsets our lifestyle," Marra said. "And what they want to do is create as much havoc as they could."
After 9/11, as security was beefed up at government buildings, airports, and sports arenas, militants have turned to easier targets.
In 2013, it was a luxurious shopping mall in Kenya. This summer, a tourist beach in Tunisia. And in Paris on Friday night, more soft targets.
In New York City Saturday, police were out in force, hoping to deter the same thing from happening here.
"Isn't this a good sign that even less than 24 hours after an attack in Paris, people are out living their lives," Moriarty said of the crowd in Times Square.
"That's what New York is all about," Marra said. "We're resilient people and although we've had things happen here, we forget and we move on."