After the 2016 election, the public learned to be wary of social media, where tricksters masked their identities to spread false and inflammatory information. Now, experts warn that video footage — once the gold standard for verification — may be manipulated ahead of 2020.

So-called “deep fake” videos don’t require much money, time, or specialized training to make. Free software allows users to swap faces in videos, with early use made of it in X-rated content. Researchers are working to build detection tools before the videos appear in politics.