In a letter appearing online Thursday, Facebook CEO Mark Zuckerberg and his wife Priscilla Chan write that President Trump’s “divisive and incendiary rhetoric” has left them “deeply shaken and disgusted” in a volatile time that they say requires “unity” in the U.S. Writing under the letterhead of their Chan Zuckerberg Initiative, which focuses on technology solutions to social problems, the couple were responding to last week’s call by more than 270 scientists that Facebook address what the scientists described as “misinformation” appearing on social media. A copy of the Chan-Zuckerberg letter was posted on Twitter by Recode journalist Teddy Schleifer.