Compared to 15 years ago, "we're safer in certain ways, but not as safe in other ways," Giuliani said on ABC's "This Week." "We're always fighting the last war. We're always fighting the last battle, the attack in the airplane. So, yes, is our airplane safety much greater today? Absolutely. Is our cargo safety much safer today? Can't tell you that."
Giuliani, who was New York City's mayor at the time of 9/11, noted that our primary enemy now is different than the al-Qaeda organization behind the attacks on Sept. 11, 2001.
"I think they've put us too much on defense, Giuliani said. "We're sitting back waiting on defense; we should be on offense."
Giuliani also defended Trump's comments at Wednesday's “Commander-in-Chief” forum in which he said ISIS would not have formed if the United States had “taken the oil” from Iraq.
Some experts have since said that taking Iraq's oil following the 2003 U.S. invasion would have violated international law.
As mayor of New York City at the time of the attack on the World Trade Center, Giuliani was widely praised for his leadership.
On Sunday, asked about a recent story in the New York Times, in which several of his former advisers said they're worried about his legacy because of his strong support for Trump, Giuliani said he's not concerned.
"I'll just say to them, 'Worry about my legacy after I'm dead,'" he said. "Right now I'm fighting for my point of view, and what I believe, and everybody has a right to do it, I'm fighting for my country."