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UNITAS 2025 began in September with an opening ceremony at Naval Station Mayport, Florida, marking the 66th iteration of the world’s longest-running multinational maritime exercise. This year’s exercise features approximately 8,000 personnel from 25 participating countries, supported by dozens of ships, submarines, and aircraft.

Training will run until October 6 and take place in multiple locations along the East Coast of the United States, including Naval Station Mayport in Florida, Marine Corps Base Camp Lejeune in North Carolina, and Naval Station Norfolk in Virginia.

Participating nations represent a broad spectrum of allies and partners, ranging from Argentina, Brazil, and Colombia in South America to Canada, France, Germany, Greece, Italy, Japan, Morocco, Spain, and the Netherlands. Smaller states such as Belize, Guatemala, El Salvador, and Jamaica are also present, demonstrating the inclusiveness of the platform and the balance of major military powers with regional partners.

The exercise featured a range of advanced assets from both navies. The U.S. contributed Arleigh Burke-class destroyers, F/A-18 fighter jets, and P-8A Poseidon maritime patrol aircraft, while Japan deployed its Izumo-class helicopter carrier, Aegis-equipped destroyers, and Kawasaki P-1 patrol aircraft. Training drills incorporated live-fire exercises, anti-submarine warfare tactics, and missile defense simulations, reflecting the combined forces’ readiness to counter potential threats in the Indo-Pacific.

Naval Station Mayport's basin has been bustling! 22 ships got underway over the past three days for #UNITAS2025.@Southcom @USNavy #Navy250 pic.twitter.com/p6rtXGK9IG

— USNAVSO_4THFLT (@NAVSOUS4THFLT) September 20, 2025

Rear Admiral Carlos Sardiello, Commander of U.S. Naval Forces Southern Command and the U.S. 4th Fleet, opened the exercise by emphasizing its historical significance. “It is a distinct honor to stand before you today as we commence UNITAS 2025, the 66th iteration of the world’s longest-running multinational maritime exercise, which is a testament to enduring partnerships,” Sardiello said.

“We have a rich history that began with the 1959 Inter-American Naval Conference in Panama, and we continue to grow each year. This year’s theme, ‘UNITAS Legacy of Maritime Partnerships, ’ celebrates the enduring strength of alliances and the upcoming 250th anniversary of the U.S. Navy,” he added.

The exercise represents more than tactical drills. It is a symbol of longstanding cooperation in the Americas, one that now includes European and Asian allies. The emphasis on legacy and history highlights how the U.S. Navy is positioning the exercise within the broader context of its own 250th birthday in 2025.

Training, Interoperability, and Operations

UNITAS is structured into multiple phases, beginning with in-port activities that include subject matter exchanges, professional symposiums, and coordination meetings. During this stage, multinational Marines and Sailors are participating in specialized training in areas such as medical support, cyber defense, and diving and salvage operations.

The exercise then moved into its underway phase, where forces are conducting operations across all domains of modern warfare. Scenarios include live-fire drills, maritime interdiction, amphibious ship-to-shore landings, and a SINKEX—short for sinking exercises, in which participating navies will fire live weapons at a designated target ship. Training also extends ashore, with simulated urban combat, force withdrawals, and amphibious raids carried out at Camp Lejeune.

“Our combined efforts as a maritime sea service are critical to ensuring free and open seas,” Sardiello explained. “UNITAS is an extraordinary opportunity for us to unite, operate, enhance proficiency, and improve interoperability of participating forces to respond to common threats.”

The amphibious portion of the drills involves forces from Argentina, Brazil, Chile, Colombia, Ecuador, Peru, Spain, and others. The climax will be a multinational amphibious landing on Onslow Beach in North Carolina, using amphibious ships from Guatemala, Mexico, Spain, and the United States.

Largest Exercises

According to the U.S. Marine Corps, this year’s exercise features its largest participation in UNITAS history, with more than 2,000 Marines and partner-nation service members. “UNITAS is a premier event for us to train alongside our allies and partners in a combined force,” said Lieutenant General Leonard F. Anderson IV, commander of U.S. Marine Corps Forces South and Marine Forces Reserve.

“This year’s exercise will help us become a more integrated naval expeditionary force with the U.S. Navy and build upon the amphibious and littoral combat power of all the participants. I am extremely proud of the work that went into the largest known UNITAS that we also have the pleasure to host.”

#Marines with @2dMarDiv take part in a medium machine gun range as part of UNITAS 2025 on @camp_lejeune.

UNITAS, which is Latin for “unity,” has taken place annually since 1960 and is the world’s longest running annual multinational maritime exercise.#Marines #SemperFi… pic.twitter.com/NXzBvd850O

— U.S. Marines (@USMC) September 17, 2025

The training extends beyond amphibious assaults and includes visit-board-search-seizure (VBSS) operations, which are designed to combat piracy, smuggling, and maritime terrorism. Participants will also engage in small-arms ranges, mortar drills, night raids, and humanitarian response simulations.

The introduction of unmanned systems, such as drones for logistical support and hybrid fleet concepts, continues from last year’s edition, reflecting the U.S. Navy’s emphasis on future-oriented technologies.

Strategic Implications in the Americas and Beyond

The UNITAS exercise takes place at a moment of heightened geopolitical competition in the Western Hemisphere. U.S. officials have noted the expanding presence of Russia and China in Latin America and the Caribbean, both in terms of military ties and economic influence.

The United States has traditionally regarded the region as part of its strategic sphere of influence, with security partnerships anchored in initiatives such as UNITAS. Recently, Washington has intensified its military activities in the Caribbean, including operations against drug cartels and joint drills with regional allies.

President Donald Trump stated earlier this month that U.S. forces had struck three Venezuelan drug boats, underscoring the link between military presence and counter-narcotics operations.

This year’s UNITAS also follows recent joint exercises with Panama, aimed at protecting the Panama Canal and other critical infrastructure. By bringing together 25 nations, the United States is reinforcing its role as the central security partner for the hemisphere while also demonstrating interoperability with European and Asian allies.

The choice to hold UNITAS in the United States, rather than in South America as is often the case, underlines Washington’s desire to showcase its capabilities directly on its own shores while hosting allies in proximity to major naval bases. The East Coast venues, Mayport, Camp Lejeune, and Norfolk, provide access to amphibious training grounds, urban combat facilities, and open waters for large-scale fleet maneuvers.

The U.S. Naval Forces Southern Command summarized the purpose of the exercise in a statement: “Through a blend of advanced warfare training, cultural exchange, and historical commemoration, the goal for the exercise is to collaboratively demonstrate the commitment to maritime security, crisis response, and the shared values that unite all participating forces in the defense of freedom and global stability.”

US Navy’s 250th Anniversary

The conclusion of UNITAS 2025 will transition directly into commemorations of the U.S. Navy’s 250th birthday, a milestone that underscores the service’s evolution since its founding in 1775. Celebrations will include high-profile events along the East Coast, as well as additional exercises and port visits into 2026, when the United States marks its own 250th anniversary.

The Navy has positioned UNITAS not only as a tactical exercise but also as a symbolic event linking history, legacy, and future strategy. The involvement of so many partner nations highlights the U.S. Navy’s ability to convene allies and reinforce shared commitments at a time of global uncertainty.

Lieutenant General Anderson framed the importance of the exercise in these terms: “This year’s exercise will help us become a more integrated naval expeditionary force with the U.S. Navy and build upon the amphibious and littoral combat power of all the participants.” His remarks, paired with Sardiello’s emphasis on partnerships, reinforce the dual purpose of UNITAS: strengthening practical interoperability while also affirming the values of cooperation and collective defense.

As the exercise unfolds, observers will be watching how participating countries apply lessons from UNITAS to their own defense strategies, and whether the United States will expand its regional exercises in the months ahead to counter growing external influence. For now, UNITAS 2025 stands as the clearest expression of the U.S. Navy’s enduring role as both a global maritime power and a regional security guarantor.