Millions of US visa applicants will now have to submit their social media names under new rules.
The increased security measures will demand applicants to submit all social media names and five years' worth of email addresses and phone numbers.
Failure to do so will result in "serious immigration consequences", according to officials.
The change, first announced last year and taking effect this month, follows on a 2017 order by US President Donald Trump requiring heightened vetting for visa applicants, according to a State Department official.
An estimated 14 million travellers and 710,000 immigrants to the US each year will be affected by the changes, according to notes in the Federal Register.
The official said national security is the top priority and every would-be traveller or immigrant who already faced screening, will be required to list their travel history, family member information, and previous addresses.
The American Civil Liberties Union had opposed the proposal, arguing the questions would create "an environment ripe for profiling and discrimination."
Previously, only applicants who needed additional vetting, such as people who had been to parts of the world controlled by terrorist groups, would need to hand over this data.
Some diplomatic and official visa applicants will be exempt.
