Gen. John Campbell, the top commander of U.S.-led forces in Afghanistan, said that a “younger piece” of the Taliban in Afghanistan may seek to join forces with the Islamic State despite the ideological differences between the two jihadist groups.

In an exclusive interview with The Hill, Gen. Campbell said he is “worried” about a resurgence of terrorists in Afghanistan, adding that the U.S. and Afghan forces have to keep the pressure on.

Although the Taliban and the Islamic State (IS, ISIS, or ISIL) do not share the same ideologies, a “younger piece” of the Taliban would look for opportunities to join forces with ISIS and “bring that into Afghanistan,” predicted the general.

“Again, another reason to keep the pressure,” he also said, later adding, “This continues to be a very dangerous place, and the Afghans continue to be at war.”

The Hill noted that Gen. Campbell “avoided giving a definitive answer” when questioned about the possibility of Afghanistan becoming a safe haven for terrorists again.

President Obama confidently told troops in Hawaii on Christmas Day that Afghanistan “is not going to be a source of terrorist attacks again.”

Islamic State (IS, ISIS, or ISIL) jihadists are already operating in Afghanistan’s Helmand province, near the birthplace of the Taliban along the country’s border with Pakistan.

Gen. Campbell told The Hill that the U.S. “still has two years to build the capability of Afghan forces, even as American troops continue to withdraw.”

U.S. troops drew down to 10,600 by the end of last year.

Obama ended the U.S.-led combat mission in December, at the end of the deadliest year of the Afghanistan war.

Campbell told The Hill that in December, Taliban rocket attacks on Bagram Airfield near Kabul reached a historic level when compared to other periods of the Afghanistan war, which started more than 13 years ago on Oct. 7, 2001.

“It’s not combat, but it continues to be a very dangerous environment that we have our soldiers in,” Campbell said.

The new train and assist mission for U.S.-led forces in Afghanistan officially started at the beginning of this year. It does include a narrower counterterrorism component.

“The [Obama] administration has been steadfast about maintaining its troop drawdown schedule,” reported The Hill. “Campbell said his intelligence, surveillance and reconnaissance assets, such as spy planes and drones, are also going down, having been reduced 65 percent since 2011.”

If necessary, Campbell said he would amend the drawdown schedule, but emphasized that the “Taliban are losing.”

“I still want to see what we can do with 9,800 and continue to train, advise and assist at that level for as long as we can go. And then make sure we have a responsible drawdown,” explained the general.

Afghan President Ashraf Ghani suggested that Obama “re-examine” the U.S. military drawdown schedule.