“China threatens to shoot Nancy Pelosi’s plane down if she visits Taiwan.”

With tensions running high over a potential visit to Taiwan by House Speaker Nancy Pelosi, who-said-what misinformation is spreading on social media.

"China threatens to shoot Nancy Pelosi’s plane down if she visits Taiwan," says a July 31 post on Instagram. It was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Facebook.)

The statement did not originate with China’s government. It was tweeted by Hu Xijin, former chief editor of and now a commentator for the Global Times, a Chinese nationalist...