The U.S. government may impose tighter scrutiny of visa-seekers' social media accounts following revelations that one of the San Bernardino attackers discussed violence before she was allowed into the country, NBC News reports.

"It's safe to assume that in the wake of this tragic incident that we're all going to be taking a hard look at the social media aspect of this," State Department spokesman John Kirby told reporters Monday.

American consular officers are already permitted to review applicants' social media activity if they think it to be "valuable or necessary." The decision is made on a case-by-case basis and is not mandatory, Kirby said.

A stricter regulation could make such scrutiny a regular step in the approval process. But Kirby pointed out that people can also disguise their identities online or turn on privacy settings that would prevent an officer from seeing much.

The Department of Homeland Security, the other federal agency that reviews visa requests, is also working to add social media to the background checks, officials said, according to NBC.

The new protocols are being considered following the December 2 attack in San Bernardino, California, in which a radicalized Muslim couple gunned down 14 people at a holiday office party.