U.S. Defense Secretary Pete Hegseth installed the Signal messenger on a Pentagon computer, circumventing internal security rules that prohibit the use of personal apps in the department's secure areas, The Hill reported on April 25, 2025, citing several sources close to the department's leadership. According to them, Hegseth and his aides were looking for ways to speed up communication with the White House and other senior officials outside the Pentagon, where mobile communications and third-party messaging programs are restricted for security reasons.

To circumvent these restrictions, in early March 2025, Hegseth ordered a special cable to be installed on his computer, which would allow him to bypass the ban on installing third-party software. This equipment, according to sources, made it possible to synchronize his Signal account with his mobile phone, effectively duplicating the messenger's functions on his work device. Similar cables were used by the secretary's aides, which allowed them to also use Signal for operational communications. However, the Pentagon, in an official response to The Hill, denied the presence of the messenger on Hegseth's computer, insisting on compliance with all security protocols.

The incident has raised concerns in Congress, with some lawmakers calling for an investigation into possible cybersecurity breaches, Politico reported. The use of Signal, known for its end-to-end encryption, outside of the Pentagon’s strict rules raises questions about the protection of classified information, especially as the U.S. coordinates military aid to Ukraine and debates sanctions against Russia. The Pentagon has seen previous data breaches in 2023, according to The Washington Post, leading to increased scrutiny of unauthorized apps.

Previously, as The New York Times reported, similar violations were recorded in other departments, including the State Department, where employees used personal devices to work with classified data.