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Republican South Carolina Sen. Lindsey Graham renewed his calls on technology companies to give law enforcement entry into its encrypted information to fight terrorism. His message to Silicon Valley: “Change your business model tomorrow.”

Graham said encryption on consumer devices is leaving the U.S. vulnerable to attacks. He cited an incident from May of this year when two gunmen opened fire outside a Prophet Muhammad cartoon contest in Garland, Texas. The FBI argued encryption stymied the probe.

“One of the shooters in Texas … had 109 messages sent between him and a known terrorist overseas that we could not look at because of encryption,” Graham told Fox News’s Greta van Susteren. “There is technology available to terrorists where they can communicate without — even with a court order, they can communicate without us knowing. That has to change.”

Companies like Apple and Google have bolstered encryption on smartphones because of heightened consumer privacy concerns in the wake of Edward Snowden’s revelations that the government had been spying on its citizens. Graham said that’s a business decision.

“Here is my message to Silicon Valley,” Graham said. “Change your business model tomorrow.”

The senator’s challenge isn’t new, but the terror attacks in San Bernardino and Paris, just weeks apart, have heightened the rhetoric, with encryption coming to the forefront. Still, critics argue the tech industry itself has become a convenient political mark.

Apple, Google and Facebook have all been under mounting pressure to create backdoor keys that would allow law enforcement access to encrypted communications. The companies maintain that this change would make consumers vulnerable to hackers and cyber crime.

Apple changed its encryption policy in 2014 with the introduction of its iOS 8 mobile operating system for iPhones, iPads and iPod touch devices. The company began encrypting communications between its devices, so whenever a person uses iMessage or FaceTime, those messages are encrypted on the device in such a way that they can’t be accessed without a passcode — and Apple has no way to decrypt those messages.

Google offers similar encryption on mobile devices powered by its Android operating system.