“Radical jihadist groups, the same people who carried out the attacks in Paris, who inspired the attacks in California, are trying to use our immigration system against us,” Rubio said Thursday to a crowd packed into a Bedford home.

“They’ve already gotten someone into this country as a fiancee,” he said, referring to Tashfeen Malif, the wife accused in the California shootings. A Pakistani citizen, she was allowed into the country in 2014 to marry a U.S. citizen. The FBI said after the shooting that Malif and her husband had been radicalized for some time, but the FBI also said recently there’s no evidence of outside actors in coordinating the shooting.

Rubio says if the government doesn’t know “100 percent” who someone is or why they are coming into the United States, they won’t be allowed in under his administration.

“This has become a national security issue, and when an issue changes, so must your policies,” he said.