Questions about Brooklyn Bridge security after flags swapped out

BROOKLYN BRIDGE (WABC) -- American flags are flying once again on the Brooklyn Bridge, but the mystery remains about who climbed up there Tuesday and replaced them with white flags.

And the security breach is raising troubling questions about one of the city's most well-known landmarks.

"It was compromised and I think that everybody should be asking, 'What should we do going forward?", said security expert Nicholas Casale.

That question focuses on security for the 4,000 who walk it every day, the 120,000 that drive over it, and the overall protection of the historic bridge.

This after two American flags at each end of the bridge were replaced with two large white flags early Tuesday morning.

"There was no anxiety on their part. They were comfortable. They knew they weren't going to get detected. So they not only did the north tower but they also did the south tower," said Casale.

A security expert with Casale Associates and a former NYPD detective, Casale wonders if they stole flags this time, what else could they have breached.

"At this time it appears it has no particular nexus to terrorism," said John Miller, Deputy NYPD Commissioner for intelligence and counterterrorism.

Police now say they are looking for five men in their early 20's, one of them carrying a skateboard. Beyond that, they add their motive is not clear.

"No matter what the motive was, that is a matter of concern. I am not particularly happy about the event," said NYPD Commissioner William Bratton.

"There should have been some trip lever that would have generated an immediate response, and that wasn't in place," said Casale.

He believes there should be a complete reevaluation of security measures that he says were put into place after 9/11. And that, he adds, should be done often.

"We can't live in the belief that we're secure. We always have to re-challenge our security," said Casale.