The leader of New York City on 9/11 reflected on the war against terror 16 years after the World Trade Center was destroyed.

Former mayor of New York City Rudy Giuliani remembered on the anniversary of the terror attack Monday how hard it was for the city, but also how people rushed to support New York.

"The reality is that's the spirit of America, that when we get attacked we all stick together," Giuliani told "Fox & Friends."

"You see that in Texas. You see that in Florida," he added, referencing hurricane relief efforts underway in those states.

The former mayor said he is not surprised the war against Islamic terrorism has lasted so long.

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"The motivations that caused that attack are still a danger to us," he warned.

"This enemy is a different kind of enemy. They're very determined, very patient," Giuliani continued. "They see this as an eternal mission."

"It's something that's still going on. This isn't yet part of our history."

However, it says something about U.S. intelligence and the military that the country has not had an attack like 9/11 since, he concluded.

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