A magazine journalist’s account of being added to a group chat of U.S. national security officials coordinating plans for airstrikes has raised questions about how highly sensitive information is supposed to be handled. Atlantic Editor-in-Chief Jeffrey Goldberg detailed a discussion that happened over the Signal messaging app hours before strikes on Iran-backed Houthi-rebels in Yemen ordered by U.S. President Donald Trump. The National Security Council has since said the text chain “appears to be authentic” and that it is looking into how a journalist’s number was added to the chain.

what is signal?

It’s an app that can be used for direct messaging and group chats as well as phone and video calls. Signal uses end-to-end encryption for its messaging and calling services that prevents any third-party from viewing conversation content or listening in on calls. In other words, messages and calls sent on Signal are scrambled and only the sender and recipient at each end will have the key to decipher them. Signal’s encryption protocol is open source, meaning that it’s freely available for anyone to inspect, use or modify. The encryption protocol is also used by another popular chat service, social media company Meta’s WhatsApp platform.

Signal touts the privacy of its service — and experts agree it is more secure than conventional texting. But it could be hacked.

Government officials have used Signal for organizational correspondence, such as scheduling sensitive meetings, but in the Biden administration, people who had permission to download it on their White House-issued phones were instructed to use the app sparingly, according to a former national security official who served in the administration.