Sea Power United as NATO’s Neptune Strike 25-3 Tests Interoperability Across Europe’s Maritime Sphere.

NATO kicked off Neptune Strike 25-3, fielding 10,000 troops from 13 Allies across four seas to test interoperability and secure key maritime chokepoints.

NATO has launched Neptune Strike 25-3, a major multinational exercise bringing together more than 10,000 troops from 13 Allied nations. Conducted from 22-26 September across the Mediterranean, Adriatic, North and Baltic Seas, the drill aims to test interoperability, ensure freedom of navigation and secure strategic chokepoints. In an era marked by renewed great power competition and contested maritime domains, this exercise underscores the Alliance’s commitment to collective deterrence and the defense of vital sea lanes. Its scope and scale make it one of the most significant demonstrations of NATO’s maritime strike integration in 2025.
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Neptune Strike 25-3 consolidates NATO’s ability to project credible deterrence while offering a visible reassurance to Allied nations bordering contested waters. Through the participation of diverse naval forces, from the U.S. Gerald R. Ford Carrier Strike Group to Türkiye’s Anadolu Task Group, the exercise symbolizes the Alliance’s unity and its operational depth (Picture source: NATO)

Neptune Strike’s latest run is underway under the direction of Naval Striking and Support Forces NATO in Oeiras, Portugal, led by U.S. Vice Adm. Jeffrey T. Anderson. The outline of the operation comes from STRIKFORNATO briefings and participating navies’ public notes. A Carrier Strike Group and a broad mix of amphibious and surface units fall under NATO operational control for the duration. At the center of the action are the U.S. aircraft carrier USS Gerald R. Ford, Türkiye’s amphibious assault ship TCG Anadolu, Italy’s landing ship ITS San Giorgio, and the U.S. command and control flagship USS Mount Whitney. Around them, a moving ring of destroyers, frigates, submarines and aircraft from Denmark, Estonia, Finland, France, Germany, Italy, Lithuania, Norway, Poland, Türkiye, Sweden, the United Kingdom and the United States shuttles between serials, showing how wide NATO’s maritime net can stretch when asked.

Attention this time gravitates to TCG Anadolu and the task group built around it. Ankara has paired the ship with the frigate TCG Gökova, the corvette TCG Heybeliada and the submarine TCG I. İnönü, a compact mix that lets planners test escort profiles, undersea screening, and aviation handling on a short leash. Turkish officers describe this as an Open Sea Task Group model, the kind of formation they have taken to sea before, including combined activity with Spain in 2024. The choice to bring that template into a broader NATO setting is practical. It lets the group rehearse launch and recovery cycles, small boat movements, and the mundane but vital logistics that make an amphibious ship earn its keep.

Neptune Strike traces its institutional roots to Project Neptune in 2020, an effort to knit together allied strike assets quickly, then keep them knitted through a steady drumbeat of deployments. Since then the exercise has come back in regular pulses. Crews now know the rhythm. The third iteration this year follows a July to August cycle and carries the same core intent: move large pieces early, lock in command relationships, and keep communications paths clean when the sea space gets crowded. None of this is flashy, but it shows in the way air tasking orders are cut and in the speed at which escorts shift stations around the carrier or the amphib.

The technical value sits in the seams. Carrier air wings practice cyclic sorties under an allied umbrella while the staff aboard USS Mount Whitney runs the data plumbing that ties ships, aircraft, and submarines into one picture. On the waterline, the amphibious teams run well-traveled drills that never stop mattering: boat insertions, casualty handling, replenishment at sea with odd pairings of ships that do not meet each other often. Submarines from several navies prowl the boxes assigned to them and force the surface side to keep active and passive sensors honest. That is the day job here, refining interoperability until the handoffs feel routine.

There is a broader point. Running the exercise from seas that link Europe’s north and south lets NATO test coverage over the chokepoints that everyone watches, from the Danish straits to the funnel into the central Mediterranean. The message is not subtle. If needed, the alliance can concentrate a carrier group, an amphibious group, and the usual screen of escorts in more than one theater at once. In a year when tension is high in Eastern Europe and in the Black Sea’s shadow, and when commercial shipping routes carry extra political weight, the signal about freedom of navigation and readiness to protect it lands where it is meant to land.

For allies on the edge of contested waters, the reassurance is also part of the package. Seeing the U.S. Gerald R. Ford Carrier Strike Group share water with Türkiye’s Anadolu Task Group, and watching European escorts swap roles across national lines, tells a simple story about capacity and depth. Exercises end, ships peel off, and everyone goes home to maintenance and budgets. What stays behind is the muscle memory: the call signs, the frequencies, the diagram of how fast a mixed formation can move when the order comes. That is the durable outcome of Neptune Strike 25-3 and the reason it keeps returning to the calendar.

Written by Teoman S. Nicanci – Defense Analyst, Army Recognition Group

Teoman S. Nicanci holds degrees in Political Science, Comparative and International Politics, and International Relations and Diplomacy from leading Belgian universities, with research focused on Russian strategic behavior, defense technology, and modern warfare. He is a defense analyst at Army Recognition, specializing in the global defense industry, military armament, and emerging defense technologies.