Homeland Security Orders Increased Security for Government Buildings

Secretary Jeh Johnson says the measure is a "precautionary step."

"Given world events, prudence dictates a heightened vigilance in the protection of U.S. government installations and our personnel," he said.

Johnson also urged state and local governments and operators of "critical infrastructure" to be vigilant, particularly against potential "small-scale attacks by a lone offender or a small group of individuals."