As geopolitical tensions in Europe evolve, NATO Allies and the United States Army are ready to protect the Alliance’s eastern flank.
Dynamic Employment of Forces to Europe for NATO Deterrence and Enhanced Readiness (DEFENDER) 25 began in April 2025 with the deployment of U.S. personnel and equipment to Europe. The goal is to test how quickly the U.S. military can mobilize forces across long distances, maintain operations and support its Allies from the Arctic to the Mediterranean and Black Sea regions.
DEFENDER is the largest U.S. Army exercise in Europe and is designed to confirm the Alliance’s ability to deny aggressors. It also reinforces the U.S. commitment to NATO’s defense strategy while enhancing combat capability to deter with power.
“This is about global deterrence,” Gen. Christopher Donahue, commander of U.S. Army Europe and Africa, said in a U.S. European Command news release. “Everything we demonstrate we can do with our Allies and Partners we can pick up and do anywhere. DEFENDER gets us sets and reps at theater logistics and warfighting at scale that isn’t being done anywhere else right now.”
DEFENDER, now in its sixth iteration, deploys 5,400 troops and equipment from the U.S. to overseas training areas. It sets the stage for large-scale exercises led by U.S. Army Europe and Africa during May and June 2025 that will bring together 25,000 troops from 29 Ally and Partner nations for three major exercises designed to improve coordination, tactics and interoperability.
Exercises include Swift Response, Immediate Response and Saber Guardian. Swift Response is led by U.S. Army Europe & Africa and focuses on allied airborne forces’ ability to quickly and effectively respond to crises as an interoperable, multinational team. Operations will take place in Finland, Latvia, Lithuania, Norway and Sweden. Swift Response also includes a hospital exercise, high mobility artillery rocket systems rapid infiltration training, air assaults and experimentation.
During Immediate Response, DEFENDER’s second phase, 12,000 U.S. Allies and Partners will assemble during theater opening activities to reinforce cyber defenses and demonstrate security capabilities while continuing NATO integration. The exercise includes multinational cyber fires conducted on NATO networks, a cyber exercise, a river crossing and defense protection exercises hosted in Albania, Bulgaria, Croatia, Greece, Kosovo, Montenegro, North Macedonia and Slovakia.
In addition to NATO, several Partner nations are supporting the exercises. In early April 2025, the Armed Forces of Bosnia and Herzegovina (AFBiH) and the Maryland National Guard completed a logistics exchange sharing best practices for vehicle maintenance, convoy operations, traffic management and sustainable logistics. The exchange was part of the National Guard Bureau’s State Partnership Program.
“I could not be more excited to be over here with our team supporting this State Partnership Program event with Bosnia and Herzegovina — a partnership we’ve had for more than 20 years,” said Maryland Air National Guard Brig. Gen. Drew Dougherty, the assistant adjutant general – air. “It has been a great opportunity for our group of Airmen and Soldiers to participate in this mutually beneficial exchange, one that will help set up AFBiH for success during their upcoming U.S. European Command exercise with us next month.”
DEFENDER’s third phase, Saber Guardian, enhances NATO’s land component mission command and improves coordination among Allies and Partners in a fast-moving environment. Beginning with a long tactical road march, the realistic, multidomain training brings together some 10,000 multinational troops and takes place in Czechia, Hungary and Romania. The exercise includes convoys, river crossings, live-fire events and a rocket fire exercise.
By strengthening teamwork and military readiness, these exercises help ensure NATO and U.S. forces can respond decisively to dominate and win against military forces that threaten NATO member sovereignty.