What is terrorism?

Speaking on Sunday, New York City Mayor Bill de Blasio held off on calling the bombing in Chelsea that hurt 29 people "terrorism." But with suspect Ahmad Khan Rahman in custody on Monday, de Blasio said: "We have every reason to believe this was an act of terror."

Was avoiding the term the mayor's way of putting New Yorker's minds at ease or was it an attempt not to jump to conclusions? People we spoke to say in their minds it was obvious all along.

Julian Ku, professor of Constitutional Law at Hofstra Law School, said if it was something done intentionally, it is safe to say terror. He said the question is what kind of terrorism? Domestic, international, Islamic? Ku said the goal of a terrorist is to scare and disrupt society. That motivation is always the same. 

Ku said that what makes terrorism different legally is that the terrorist hopes to accomplish a political goal. It can be international foreign policy or domestic.

President Obama called New Yorkers tough and resilient. New Yorkers we spoke to agreed.