Potential 2016 Republican presidential candidate Ben Carson said in a radio interview recently that he fears a Muslim alliance could take down the United States. Speaking Wednesday on conservative host Hugh Hewitt's syndicated show, the former neurosurgeon said he fears a reunion of Shiite and Sunni Muslims.

“Right now, they’re fighting each other in Iraq, admittedly,” Carson said, according to the Hill. “But in the long run, I think they would gladly unite against us in their attempt to destroy the United States, our way of life, and Israel. And we have to be extraordinarily careful about any alliances with them.”

Followers of Islam split into two groups, the Shiites and Sunnis, shortly after the Prophet Muhammad's death in 632. Between 87 and 90 percent of the world's 1.57 billion Muslims are Sunni, according to a 2009 Pew Research Center study. For centuries, the groups' relations have been strained, recently coming to a head with the rise of the extremist Islamic State group in the Middle East. 

In Iraq, some Sunnis have been helping the group -- which is also known as ISIS or ISIL -- and the ones who aren't doing so say the nation's government isn't helping them enough. Shiites have been fighting ISIS but could be using the conflict to gain control of Sunni-dominated cities, according to the Associated Press.

Carson said the ISIS-aligned Sunnis are dangerous, and so are Iran-based Shiite terrorist groups, Mediaite reported. He said the factions are undoubtedly in a power struggle, but that doesn't mean they're not a threat to the U.S. “There’s no question they’re at each other’s throats,” he said. “And it’s tempting for us to say, you know, the enemy of our enemy is our friend. But I do not believe that for one second. I believe that they believe that we are evil, and they want us destroyed.”

Listen to the full, 17-minute interview below: