New York City Police Department Commissioner Ray Kelly spoke with John Gambling this morning for an exclusive discussion on heightened security in light of Boston's tragic act of terrorism yesterday.

"We've done more and we've invested more in protecting ourselves from terrorism than any city I'm aware of," Kelly assured listeners.

The commissioner also noted that the duration and strength of additional security will be "based on developing information."

"It's not an inexpensive undertaking, so we have to factor that in," he said. "Certainly on a day like today we think it's appropriate."