What does 'continuous vetting' mean for US visa holders

Washington

: A

State Department

statement Thursday saying that all holders of valid U.S. visas would be subject to “continuous vetting” sounded like a dire warning to the more than 55 million foreign nationals who have permission to be in the United States.
But with few details about how the department plans to execute the effort, it was unclear if the pronouncement heralded a drastic culling of travel documents and acceleration in deportations, or something less.