FBI head says no evidence San Bernardino attackers were part of terrorist cell

There is no evidence a married couple who killed 14 people in California this month were part of a terrorist cell, the head of the FBI said on Wednesday, echoing investigators' views that the pair were inspired by, rather than organized by, Islamic State in Iraq and Syria (ISIS).

The Islamist militant group has "revolutionized" terrorism by seeking to inspire such small-scale attacks, FBI Director James Comey said, noting the group uses social media, encrypted communications and slickly produced propaganda to recruit followers around the world.

"Your parents' al-Qaeda was a very different model than the threat we face today," Comey told a counterterrorism conference in New York.

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However, he said that while the perpetrators of the Dec. 2 shootings in San Bernardino, Calif. Syed Rizwan Farook, 28, and Tashfeen Malik, 29 had expressed support for "jihad and martyrdom" in private communications, they never did so on social media.

Just days after the attack, authorities said they were looking into an apparent Facebook post in which Malik had pledged allegiance to ISIS leader Abu Bakr al-Baghdadi.

Multiple U.S. media outlets reported Malik had expressed "admiration" for al-Baghdadi, but it was under an account that used a different name. The messages were reportedly deleted before the attack, and Facebook quickly removed the account in the wake of the shooting.

Comey said the Federal Bureau of Investigation currently has "hundreds" of investigations in all 50 U.S. states involving potential Islamic State-inspired plots.

His remarks came as Americans are jittery two weeks after the San Bernardino attack. Islamic State is based in Iraq and Syria, where it controls a large area of territory as it seeks to carve out a caliphate. It claimed responsibility for attacks in Paris on Nov. 13 that killed 130 people.

Comey said the group has perfected the use of social media, and Twitter in particular, to contact potential followers in the United States and elsewhere.

"Twitter works as a way to sell books, as a way to promote movies, and it works as a way to crowdsource terrorism to sell murder," Comey said.

Islamic State also employs "end-to-end" encryption when communicating with individuals who it believes are willing to carry out killings in its name, Comey said.

That has posed a significant challenge for investigators, who often find themselves stymied even when they have court orders giving them access to devices.

But Comey said he is convinced that law enforcement and technology companies can work together to solve that problem without compromising personal privacy.

"We are not going to break the internet," he said. "We are not going to jeopardize people's security."

Farook and Malik were buried Tuesday in a quiet, graveside funeral hours away from San Bernardino guarded by FBI agents. Many of those who attended mosque with the couple refused to attend, two mosque members said.

The White House announced Wednesday President Barack Obama plans to meet with families of victims of the mass shooting.

The meeting is set for Friday, and Obama is adding the stop in Southern California to a long-scheduled trip to Hawaii for Christmas vacation.