A person using an AI-generated voice to impersonate U.S. Secretary of State Marco Rubio contacted multiple high-ranking officials last month, according to Reuters.

The individual reached out to three foreign ministers, a U.S. governor, and a member of Congress via the Signal messaging app, leaving voicemails for at least two of the targets in mid-June.

The cable, dated July 3 and circulated to all U.S. diplomatic and consular posts, warned that the impersonator likely aimed to manipulate officials using AI-generated voice and text in an attempt to gain sensitive information or access to official accounts. In at least one case, a text message was sent to encourage the recipient to switch to Signal for further communication.

A senior State Department official confirmed the incident is under investigation, adding that the department is taking steps to strengthen cybersecurity and prevent similar incidents. “There is no direct cyber threat to the department from this campaign,” the official said, “but information shared with a third party could be exposed if targeted individuals are compromised.”

While the identity of the perpetrator remains unclear, the cable referenced a separate phishing campaign from April that was linked to a Russia-affiliated hacker. That attempt, targeting think tanks and former U.S. officials, involved spoofed “@state.gov” email addresses and official-looking logos to impersonate the State Department’s Bureau of Diplomatic Technology.

The cable noted that the attacker demonstrated deep familiarity with internal State Department protocols, including naming conventions and document formats. Messages in that campaign were sent to personal Gmail accounts and were later attributed to a group associated with the Russian Foreign Intelligence Service.

The new impersonation case comes just weeks after The Wall Street Journal reported a similar attempt to impersonate White House adviser Susie Wiles, raising fresh concerns about the growing misuse of AI in political and diplomatic espionage.