Puerto Rico was an “Exceptional Training Location” for Counterintelligence Exercise, New Documents Reveal
The Army Reserve said it was not able to provide more documents, “in part,” because records were “not properly archived.”
If you made your way through masses of tourists to enjoy the breeze and beaches of San Juan during the summer of 2023, there's a chance you might have unknowingly passed right next to counterintelligence agents honing their craft.
Documents I obtained reveal new details about Vigilant Defender 23, the "largest counterintelligence training event in US Army Reserve Command history." The exercise was hosted by the 752nd Military Intelligence Battalion (Counterintelligence), Interrogation Group, and Military Intelligence Readiness Command (MIRC).
“Puerto Rico provided an exceptional training location offering language and environment complexities for attendees to navigate,” reads one of the documents obtained through a Freedom of Information Act (FOIA) request.
A summary of the event explained that “more than 150 participants” were evaluated on several tasks crucial to counterintelligence, such as communicating with sources, conducting surveillance on a target, and managing operations. Some participants were subdivided into 3- or 4-person counterintelligence teams, then given a scenario based on espionage, treason, or an insider threat, and told to investigate the lead fully. Meanwhile, personnel from the 752nd, Army Counterintelligence Command, and federal law enforcement, like the FBI and Homeland Security Investigations, provided oversight and management of the exercise.
Redacted photos included in the documents show participants receiving training and enjoying their time on the archipelago, best exemplified by one photo that shows them posing in front of an “I Love PR” sign. Two of the photos show agents surveilling a target of an investigation. It is unclear if all the people pictured in the photo were part of the training or if some are civilians.
A post on the US Army website — seemingly one of the few public acknowledgements of Vigilant Defender 23 — notes that units “tailored” their training “around conducting operations in a true Spanish language environment.” Agents were also trained in directing the “utilization of interpreters/translators” and leading the “integration of an interpreter/translator,” according to a list of evaluated tasks included in the documents. The Army post recognizes that working with interpreters and overcoming language barriers led to “enhanced realism” for the training exercise, making them “more adaptable and resilient to different environments.”
The records received by Heavy Weather mention 180 written reports, 110 interviews, several threat briefings, a “custom-built Teams channel,” and a “role player academy” that were conducted throughout Vigilant Defender 23. However, none of those documents were included in the release “in part” because “the individuals who led this exercise are no longer available to provide records” or there are “communications that [were] not properly archived prior to the personnel’s departure,” according to the response to my FOIA request.
The FOIA request was for instructional materials, presentations, and internal documentation relating to Vigilant Defender 23. The request also asked for communications shared with local, state, and federal agencies inviting them to participate.
While it is unclear what role they took, the post on the Army website mentions that local police were "brought in" to the event. However, it is unclear if they participated in the event or simply discussed it with the participants because the documents do not mention the Puerto Rican police.
Vigilant Defender 23 took place between July 8 and July 22, 2025, and was part of the Army Reserve's annual training. While it’s unclear what specific role they took, personnel from European Command, Medical Command, 7th Psychological Operations Group, and the Puerto Rico National Guard also participated in the event. Over 210 people participated in the exercise, according to the documents.
"We really hope that Vigilant Defender becomes the flagship counterintelligence event on an annual basis," said Major Dan Burnett, 752nd Military Intelligence Battalion (Counterintelligence) operations officer, in the US Army blog post.
MIRC did not respond to an emailed request for comment.
While typically done by federal law enforcement, Vigilante Defender 23 is just one in a long history of intelligence and counterintelligence operations that were based out of Puerto Rico. Both the FBI and the CIA surveilled pro-independence activists throughout the 2oth century as part of COINTELPRO and Operation Chaos, respectively. For decades, the Puerto Rican police and the FBI collaborated in a mass surveillance program colloquially called las carpetas (the files). Between 1.5 and 1.8 million pages of surveillance material were created on over 100,000 people. Meanwhile, the 2013 Snowden leaks revealed Puerto Rico served as a "center of covert spying for several Latin American countries" for a joint CIA and National Security Agency operation, according to Puerto Rico’s Center for Investigative Journalism. A counterintelligence memo linked a CIA cell composed of agents and Cuban exiles to the bombing of a Puerto Rican Socialist Party event.
Heavy Weather currently has several FOIAs out on military and federal law enforcement operations. You can find the Vigilant Defender 23 documents I obtained for this story below:
