Officials past and present, including former Mayor Rudolph Giuliani, took part in a Congressional hearing Tuesday at the site of the September 11th attacks. NY1's Bobby Cuza filed the following report.

It's been almost 14 years since he left office, but when it comes to terrorism, former Mayor Rudolph Giuliani is still considered an authority.

Tuesday, he was the marquee witness at a Congressional hearing on the post-9/11 terror threat, offering a sometimes grave assessment over two-and-a-half hours of testimony.

"Whatever euphemisms we want to engage in, they are at war with us," Giuliani said. "By they, I mean Islamic extremist terrorists."

The meeting of the House Homeland Security committee took place inside the 9/11 Museum at the foot of the last World Trade Center column.

To prevent another 9/11, Giuliani advocated a more aggressive approach, particularly in response to ISIS. He called Iran an even greater threat, denouncing the recent nuclear deal.

"We are putting the nuclear button in the hands of madmen," Giuliani said.

Current city officials also testified, with Police Commissioner William Bratton pointing to numerous foiled terror plots and noting a recent increase in manpower.

"Keep in mind, we lost 6,000 cops since 9/11. We didn’t gain more cops since 9/11. We lost," Bratton said. "This year, I got 1,300 more. I'm putting a lot of those cops back into counterterrorism-related activity, because the threat remains and is growing."

One NYPD strategy sent undercover officers into Muslim communities to gather intelligence. Discontinued amid controversy, Giuliani defended the program, which he first authorized.

"I believe by doing so, I saved the lives of many New Yorkers because we uncovered plots that have never come to light," Giuliani said. "I believe it was a mistake to withdraw those patrols."

One issue everyone agreed on Tuesday was the need to extend the Zadroga Act, which provides compensation and health care to 9/11 recovery workers.

On a separate note, Giuliani also pressed members of Congress to designate the 9/11 Memorial and Museum a national museum, something that would make it eligible for a regular stream of federal funding.