CIA director John Brennan
He was making the comments in an interview on NBC News on the fifth anniversary of the raid that killed Al-Qaeda leader Osama bin Laden.
"We will destroy [ISIS], I have no doubt in my mind. And we have to remove the leadership that directs that organization to carry out these horrific attacks," said Brennan, adding that if ISIS' number one, Abu Bakr al-Baghdadi, were to be killed, it would have an effect on the terrorist group.
"If we got Baghdadi, I think it would have a great impact on the organization, and it will be felt by them," he told NBC.
Brennan warned that fighting ISIS has its unique challenges, calling them not just an "organization," but "a phenomenon."
"We know that ISIS is trying to carry out attacks in Europe and in other parts of the globe. Also, we are working very, very closely with our European partners," said Brennan, who was also careful not to oversell America's ability to affect change in the Middle East.
"The United States has only limited influence to shape events in the Middle East. And a lot of individuals think that the United States can wave a magic wand, and we can't," he told NBC News.
Asked if Republican presidential candidate Donald Trump's comments about Muslims make his job gathering intelligence any harder, Brennan replied, "I focus on the mission at hand."
"I'm not distracted by it," Brennan asserted.
"The campaign is going to go on," he continued. "But one of the great things about the CIA is that we stay focused like a laser on what we need to do to keep this country safe and secure."