An imposter used artificial intelligence to mimic the voice of U.S. Secretary of State Marco Rubio, successfully contacting several high-level officials, according to a leaked diplomatic cable reviewed by Reuters.

The cable, dated July 3, reveals that in mid-June, a cyber actor posed as Rubio using AI-generated audio in outreach efforts via the Signal messaging app. The individual reportedly contacted three foreign ministers, a U.S. governor, and a member of Congress, leaving voicemails in two cases and attempting to initiate encrypted conversations in another.

According to the cable, the objective of the impersonator appeared to be information extraction through convincing AI-driven messages. “The actor likely aimed to manipulate targeted individuals using AI-generated text and voice messages, with the goal of gaining access to information or accounts,” it stated.

While there is no evidence the State Department’s internal systems were breached, the message warned that external partners could be vulnerable if deceived by such schemes. The department has urged all diplomatic and consular posts to alert colleagues and partners to the growing threat of AI-powered impersonation tactics.

This is the second incident in recent months involving digital impersonation linked to U.S. diplomatic circles. In April, another campaign—attributed to a Russia-linked hacker—targeted think tanks, Eastern European activists, and former U.S. officials. That operation used fake “@state.gov” email addresses and mimicked official branding from the State Department’s Bureau of Diplomatic Technology to bolster credibility.

“The actor demonstrated extensive knowledge of the department’s naming conventions and internal documentation,” the cable noted, highlighting the increasing sophistication of such cyber operations.

Cybersecurity experts say these incidents underscore how AI tools can be weaponized to lend a layer of realism to phishing and disinformation campaigns, making detection more difficult and consequences more severe.

The State Department has not publicly commented on the latest impersonation campaign, but officials are reportedly working closely with cybersecurity partners to mitigate potential fallout and prevent future breaches.

These incidents reflect a growing concern among national security professionals about how generative AI technologies are rapidly becoming tools for cyber deception on the global stage.