Defense Secretary James Mattis told reporters Friday that ISIS in 2018 will be seen as a "brand" for terrorists but insisted the group has lost its luster and still needs to be hunted down.

Globally, Mattis also said the DoD planned to use conventional forces more for some missions previously done by special operations teams. Special forces have increasingly been used by Washington for counter-terrorism operations in Africa and elsewhere, and the number of casualties has been growing too.

"I anticipate more general purpose forces being used for some of the missions," he said. "In the past, we used only special forces to do it. The general purpose forces can do a lot of the kind of work that you see going on and, in fact, are now."

At the same time, Mattis said U.S. forces in Iraq and Syria would shift their focus in 2018 from largely offensive missions to a stabilizing role that supports rebuilding in the war-torn region.

The secretary's remarks underscore that the Trump administration has no immediate plans to remove U.S. troops from Syria despite pressure from the Russians to do just that.

"We sit here today at the end of 2017, the caliphate is on the run, we're breaking them," said Mattis.

The U.S.-led coalition reported Friday that, from Dec. 22 to Thursday, it had conducted 46 strikes against ISIS militants in Iraq and Syria. They included the coalition attacks Wednesday in Syria that destroyed ISIS vehicles, weapons as well as communications and logistics facilities and strikes this week in Iraq that destroyed ISIS caves, tunnels and other shelters.

Mattis conceded some terrorists escaped Raqqa — the Islamic State's self-declared capital — after the city was liberated this year and are now being hunted down.

"Some people escaped," said the retired four-star Marine Corps general. "That's what happens in war. They moved, clearly, into the Middle Euphrates River Valley. We are in the process of crushing the life out of the caliphate there, while trying to keep the innocent people safe, which is very hard with this group."

Even so, fewer than 1,000 fighters from the Islamic State are believed to still be in Iraq and Syria, well below the roughly 3,000 estimated about three weeks ago, Reuters reported this week.

Mattis also was asked about the threats ISIS poses in 2018 across the globe and called it "a brand threat, I think, more than anything else, that can inspire lone-wolf attacks. It can inspire other groups."

Yet he said that "brand" now has "a diminishing appeal. It's less inspirational when they've lost their physical caliphate. It's less inspirational, as the stories of what it was like living under their rule come out."

Back in 2016, Islamic State ended the year with about 23,320 square miles of territory, according to IHS Janes estimates. Today, that number is believed to be below 2,000 square miles, according to military estimates.

Nonetheless, ISIS still poses a threat as it can continue to use social media to recruit followers that want to do harm, according to Mattis.

"The appeal is still there for people who are attracted to the sort of thing they stand for," he said.

The U.S. is still believed to have around 2,000 troops in Syria.

Russian President Vladimir Putin earlier this month announced plans to withdraw 'significant" troops from Syria, although indicated Moscow would keep bases it has in the country.

Meantime, the Russians have put pressure on the U.S. to withdraw its forces from Syria, claiming ISIS is defeated and American presence not needed.

Yet Mattis gave no indication that U.S. troops would leave any time soon.

Rather, he said U.S. forces in the region would shift their focus in 2018 from a largely offensive terrain-seizing approach to one of a stabilizing role as the military supports rebuilding and diplomatic efforts. That followed Mattis' remarking last month that there was a need to keep forces in the region to avoid an "ISIS 2.0."

"What we will be doing is shifting from what I would call an offensive, shifting from an offensive terrain-seizing approach to a stabilizing ... you'll see more U.S. diplomats on the ground," Mattis said.

One of the support roles is clearing areas retaken from ISIS of booby traps and other explosives, according to Mattis. "Just clearing these areas of IEDs is an enormous undertaking," he said. "So we're going to be training people how you clear IEDs. You don't want amateurs doing this thing. It's terribly dangerous because of the way they've constructed them and where they put them."

As for diplomats, Mattis explained that they would also help with the "initial restoration of services [since] they bring in the contractors, that sort of thing."

Mattis also said there was a need in cities and towns that were retaken from ISIS to look after essential needs, such as helping local authorities get water treatment facilities back up to prevent cholera. Other efforts include reopening schools.

"We've got a lot of money coming from international donors for this" he said. "The longer term recovery is going to take a lot of effort and a lot of years after what they did, because they forcibly kept innocent people in the midst of the combat zone, and that meant the residential areas took damage, the public areas – everything took damage. Schools were damaged."

Reuters contributed to this report.