U.S. regulators on Thursday kicked off a process that could result in mandatory disclaimers on election ads that appear on social media, a reaction to anonymous, Russia-linked ads on sites such as Facebook ahead of the 2016 U.S. elections.

The Federal Election Commission voted 5-0 to begin drafting rules that would impose disclaimers. The commission previously declined to require such labels after Facebook Inc. and Alphabet Inc.'s Google complained they would be impractical.

"Disclaimers on paid digital and internet-based advertisements are one tool identified as a mechanism for exposing foreign-paid advertisements," three Republican members of the commission said in a written motion.