In Washington, the NYPD’s commissioner for counterterrorism said law enforcement did all they could, when they first came into contact with Ahmad Rahami in 2014. Deputy Commissioner John Miller — who testified at a Congressional hearing Wednesday — acknowledges that every time someone comes on the radar, it doesn’t mean they will be able to stop them. Our Washington bureau reporter Alberto Pimienta has the story.

Ahmad Rahami had previous brushes with the law.

But authorities cannot keep an eye on everyone, that is what NYPD’s Deputy Commissioner for Counterterrorism John Miller said in a hearing on Capitol Hill.

"It’s not realistic to say every time someone comes in the radar you’re going to be able to follow them," Miller said.

Miller testified in a hearing aimed at preventing the next terrorist attack.

One of the main concerns for law enforcement is individuals who self-radicalize online.

"These messages containing these false promises resonate particularly with recruits who are failing in life, living in the margins, who have low self-esteem or feel isolated," Miller said.

New York Representative Peter King challenged Miller and questioned him about the tactics the NYPD uses.

"I don’t see how it’s considered unconstitutional or bad police work to have under covers, to have informants, the same that is done when you’re tracking any type of crime which comes from a particular community or organization," said Long Island Congressman Peter King.

"We operate on information, on behavior, on actions but we don't place under covers or spies or people into the community to watch people who are engage in completely constitutional protected activities," Miller said.

In addition, while the hearing focused mainly on the threat of lone wolves and combating terrorist propaganda online. Some lawmakers say attacks like the one in Orlando show more needs to be done when it comes to guns.

"You can’t with any credibility hold a hearing with the topic stopping the next attack," said Brian Higgins, a Congressman from upstate. "Without fundamentally addressing what most people in this panel agree with and that is very common sensical gun safety measures."  

During the hearing, law enforcement officials also acknowledged there needs to be better communication between federal, state and local authorities when it comes to preventing terrorist attacks in America.