T he Trump administration is facing heavy blowback for using Signal, a messaging app, to discuss sensitive military plans. On March 24, officials’ usage of the app was revealed after The Atlantic editor Jeffrey Goldberg published a story titled "The Trump Administration Accidentally Texted Me Its War Plans ,

Signal is a free app that cybersecurity experts consider to be one of the most secure messaging services because of its end-to-end encryption. Simply put, text messages or calls are seen only by you, the sender and whoever is in your Signal group chat.

The story of how national security officials used the Signal encrypted app to discuss a planned attack on terrorists in Yemen provides key crisis communication lessons.