https://www.theverge.com/2018/5/24/17389834/facebook-political-ad-disclosures-united-states-transparency

Facebook’s new rules regarding disclosures for political ads take effect in the United States today, requiring election-related and issue ads to include information about who paid for them. A new “paid for” label will be visible at the top of ads on Facebook and Instagram, and clicking it will take you to a page with information about the cost of the ad and the demographic breakdown of the audience that saw it.

Advertisers will also have to verify their identity and location, a move that Facebook says will discourage foreign agents from attempting to interfere in outside elections. Facebook announced new rules around ad disclosures last year after revelations that Russians had illegally run ads on the platform during the 2016 US presidential election. The company began testing its new disclosure policies in Canada earlier this year.