NEW YORK (CBSNewYork) - The attacks in Paris have raised new questions about just how terrorists operate.
And as CBS2's Dick Brennan reported, experts have also begun questioning whether the very face of terrorism is changing.
As Brennan reported, the No. 1 fear for police is the lone wolf: a person who has become radicalized, perhaps in their own living room, by reading or watching terror propaganda.
However, the Paris attacks go to new level -- involving homegrown terrorists who are traveling abroad to get training.
In just the past few months, there have been terror attacks in Ottawa, Canada; Sydney, Australia; and now Paris.
At least seven people were killed Friday, the three terrorists and at least four hostages, two days after 12 people were massacred in the Charlie Hebdo attack.
As Brennan reported, terrorists are taking their cue from jihadi propaganda, but now the message from a new generation of radical leaders also seems to have changed.
"You don't have to necessarily come to fight with us or train with us. If you can fight and attack where you are, do it," CBS Terror Analyst Juan Zarate said of the new message.
Terror experts want to know what may tie attacks together and say Paris actually seems remarkably similar to the Boston Marathon bombings in 2013.
"Not only do you have two brothers who are seemingly radicalized, either in Boston or Paris, but one goes to travel overseas, and we believe gets gets some kind of paramilitary training with some type of terrorist organization," said Mitch Silber of K2 Intelligence said, who spent eight years on the terror trail for the NYPD.
As Brennan reported, in Paris it seems as though different cells may have been acting in coordination.
"A lot of these individuals who are involved in cities in the West, we see there is almost a 'scene,' and they hang out in the scene," Silber said. "And what is in the scene? The scene is certain mosques, certain bookstores, certain cafes, maybe certain student group, certain protest activity. And these people, like free electrons, sort of bounce off of each other."
The question for authorities after Paris is now how to meet the new challenge posed by terrorists on the home front.
"The terrorism of 2015 is now a much more diverse, globally varied and organizationally-mixed environment than ever before," Zarate said.
But experts have also observed that anti-Semitic attacks, like Toulouse in 2012 or Brussels in May 2014 and now at a Paris kosher deli, seem to be continually a focal point for terrorism.
"There's some type of linkage between jihadists and Jewish targets. Obviously New York City, with a Jewish population, this has to be at some level of concern," Silber said.
That means the NYPD and other organizations will respond accordingly, covering sensitive locations with tactical teams, Brennan reported.
Late Friday, the U.S. State Department issued a global travel warning after the attacks in Paris, as well as the incidents in Sydney and Ottawa.
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