Republican presidential hopeful Ben Carson Benjamin (Ben) Solomon CarsonBiden cannot keep letting Trump set the agenda The Hill's 12:30 Report: Trump heads to New Hampshire after renomination speech Five takeaways on GOP's norm-breaking convention MORE says the screening process for Syrian migrants entering the country needs to be extensive, noting that the Boston Marathon bombers were able to enter the U.S. under refugee status.

“I would recognize that bringing in people from the Middle East right now carries extra danger,” Carson said on ABC’s “This Week” on Sunday. “And we have to be extra cautious. You know, the typical mechanisms that we use for screening people, perhaps, have to be enhanced.”

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“How does it, you know, let people like the Tsarnaev brothers in here?” he asked.

Carson has previously called for stringent background checks on any Syrian migrants attempting to enter the country.

“We have to recognize that this is a splendid opportunity for the global jihadists to infiltrate those numbers with members of their own organization,” Carson said on Saturday. “So we would have to have in place a very excellent screening mechanism. Until we had such a mechanism in place, we should not be bringing anyone in.”

President Obama has pledged that his administration will accept 10,000 migrants fleeing war-torn Syria next year.

Tamerlan and Dzhokhar Tsarnaev immigrated with their family to the U.S. in 2002 and were granted refugee status.

The brothers killed three people and injured hundreds after setting off bombs at the finish line of the 2013 Boston Marathon. They also shot and killed a Massachusetts Institute of Technology police officer while trying to flee authorities.

Tamerlan Tsarnaev was killed in the ensuing manhunt.

His brother, Dzhokhar, was captured and has been sentenced to death.