White House national security adviser John Bolton cautioned Sunday that the threat of the Islamic State will persist, and that the organization maintains a scattered presence in Syria, Iraq and other parts of the world.

Bolton, appearing on ABC's "This Week," defended President Trump Donald John TrumpOmar fires back at Trump over rally remarks: 'This is my country' Pelosi: Trump hurrying to fill SCOTUS seat so he can repeal ObamaCare Trump mocks Biden appearance, mask use ahead of first debate MORE's assessment of the terrorist group including Trump's past insistence that ISIS has been defeated and that the group had lost 100 percent of its territory.

"The president has been, I think, as clear as clear can be when he talks about the defeat of the ISIS territorial caliphate," Bolton said. "He has never said that the elimination of the territorial caliphate means the end of ISIS in total.

"We know that's not the case. We know right now that there are ISIS fighters scattered still around Syria and Iraq, and that ISIS itself is growing in other parts of the world. The ISIS threat will remain."

NEW: White House national security adviser John Bolton: "We know right now that there are ISIS fighters scattered still around Syria and Iraq and that ISIS itself is growing in other parts of the world. The ISIS threat will remain" https://t.co/azzlyEakp2 pic.twitter.com/jmJsjFuZt9 — This Week (@ThisWeekABC) March 10, 2019

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Bolton's assessment of the terrorist group's future highlights the shifting messages the Trump administration has offered since Trump announced in a video posted to Twitter in December that "we have won against ISIS" and "it’s time for our troops to come back home" from Syria.

Vice President Pence declared in January that "the caliphate has crumbled and ISIS has been defeated," and Trump has in recent weeks repeatedly spoken of the fall of the caliphate in near certain terms.

The administration announced last month plans to leave roughly 400 U.S. troops in Syria indefinitely after withdrawing its other forces from the country.

Bolton on Sunday argued the decision was part of a recognition that ISIS could regain its footing.

"One reason that the president has committed to keeping an American presence in Iraq and a small part of an observer force in Syria, is against the possibility that there would be a real resurgence of ISIS, and we would then have the ability to deal with that if that arose," he said.

Gen. Joseph Votel, commander of U.S. Central Command, told the House Armed Services Committee last week that taking back ISIS’s physical territory is a “monumental military accomplishment.”

But, he added, the fight against terrorism is still "far from over," explaining that ISIS fighters had made a "calculated decision" to preserve their efforts and wait "for the right time to resurge."

Bolton said Sunday that he's spoken with his British and French counterparts about aiding in efforts to suppress any potential ISIS resurgence, and that he's "very optimistic" the U.S. allies will join.

"It hasn't happened formally yet, but they're looking at it," he said. "I think it's very important that we try and get this up... The ISIS threat, the al Qaeda threat, the terrorist threat is an ideological threat worldwide and it's something that I think we have to be vigilant against for the foreseeable future."