BRASÍLIA, Brazil -- U.S. cyber forces participated in cyberspace operations in Brazil during SOUTHERN DEFENDER 25, a multinational cyber defense operation held from April 26 to May 8.
U.S. cyber operators trained side-by-side with Brazil’s Cyber Defense Command, marking the first time U.S. cyber operations, as part of a formal exercise, have taken place on Brazilian soil.
“SOUTHERN DEFENDER 25 emphasizes the growing scale and ambition of multinational cyber defense efforts and ensures participating nations are better prepared to respond to emerging digital threats.”
The exercise, led by U.S. Southern Command, brought together more than 300 participants from 20 countries, hosted in 15 locations. Training occurred simultaneously across four geographic combatant commands and included U.S. forces from Marine Corps Reserve units and multiple state National Guards, alongside Allied and partner militaries from South America, Central America, the Caribbean, and nations outside the Western Hemisphere.
SOUTHERN DEFENDER 25 aligned cyber events with SOUTHCOM exercises including CENTAM GUARDIAN 25, TRADEWINDS 25 and SOUTHERN STAR 25. This coordination created a training environment focused on defending infrastructure, identifying vulnerabilities, and planning effective cyber responses to malign actors in a multinational setting.
U.S. service members participate in defensive cyber operations during exercise Southern Defender 25
Photo by Cpl. Samuel Qin
U.S. Marine Corps Maj. Ben Opel, cyberspace officer, Defensive Cyberspace Operations Internal Defensive Measures, acts as the oppositional force during exercise Southern Defender 25 in Augusta, Georgia, May 6, 2025. The oppositional force emulates adversary tactics, firing scenario-based challenges at 28 teams in 15 locations consisting of 20 participating countries in real time. (U.S. Marine Corps photo by Sgt. Samuel Qin)
Support teams in Augusta, Georgia, comprised of U.S. service members, directed opposition and control elements which enabled real-time testing of cyber defenses across geographically dispersed Allied and partner forces. This structure promoted synchronized, scenario-based training to improve operational readiness, strengthen interoperability, and formalize cyber defense partnerships.
SOUTHERN DEFENDER 25 emphasizes the growing scale and ambition of multinational cyber defense efforts and ensures participating nations are better prepared to respond to emerging digital threats.