The move was intended to circumvent a lack of cellphone service in much of the Pentagon and enable easier communication between Hegseth and other Trump officials, said people familiar with the matter.

The chat app, which is run by a nonprofit foundation, has been downloaded 220 million times. Here’s what to know about Signal, including who owns it and whether it’s safe to use.

Defense Secretary Pete Hegseth denied discussing sensitive military information with his wife and others in the Signal app, saying what he shared were “informal, unclassified coordinations.”