Full Breakdown
NATO Enhances Anti-Submarine Warfare Capabilities in the Baltic Sea
11/13/2025, 8:11:27 PM
Overview of Exercise Merlin 25
NATO's Playbook Merlin 25, a significant anti-submarine warfare (ASW) exercise, is currently underway in the Baltic Sea from November 10 to 14, 2025. This exercise involves submarines, surface ships, and maritime patrol aircraft from nine NATO nations, including Germany, Sweden, France, and the Netherlands, with oversight from NATO’s Allied Maritime Command. The drill aims to enhance readiness, interoperability, and the ability to counter underwater threats in a region deemed critical for European security.
Strategic Context and Implications
The Baltic Sea has gained renewed military significance, particularly following Sweden's accession to NATO in March 2024. Rear Admiral Bret Grabbe, NATO's top submarine commander, noted that Sweden's membership has transformed the Baltic into a "lake full of NATO submarines," enhancing the alliance's collective maritime capabilities. This shift positions Sweden as a frontline state, responsible for defending not only its own waters but also the eastern flank of NATO, extending to Finland and the Baltic States.
Exercise Dynamics and Participation
The Merlin 25 exercise features a variety of assets, including a German Navy U-35 submarine, a Swedish Södermanland-class submarine, and a U.S. P-8 Poseidon maritime patrol aircraft. Surface vessels and helicopters from France, Germany, and the Netherlands are also participating. The exercise focuses on honing submarine detection skills, utilizing sonar and advanced tracking methods tailored to the unique challenges of the Baltic's shallow waters, which average only 54 meters in depth.
Sweden's Naval Modernization Efforts
Sweden is actively modernizing its naval capabilities to meet NATO commitments and address regional threats. The Swedish fleet currently includes upgraded Gotland-class and Södermanland-class submarines, alongside Visby-class stealth corvettes. However, the introduction of next-generation A26 Blekinge-class submarines has faced significant delays and cost overruns, with delivery now projected for 2031 and 2035. The Swedish Defence Materiel Administration has acknowledged the complexities and risks associated with this modernization effort.
Criticism and Challenges
Despite the advancements, Sweden's naval modernization has encountered criticism due to chronic delays and escalating costs. The budget for the new submarines has increased by over 100% since 2015, raising concerns about Sweden's ability to maintain its maritime defense capabilities amid rising tensions in the Baltic Sea. Rear Admiral Johan Norlén, Chief of the Swedish Navy, has emphasized the importance of balancing economic considerations with capacity and timeline in the development of new naval assets.
Official Statements
Rear Admiral Bret Grabbe remarked, “Baltic nations bring an impressive amount of ASW capability to NATO as well as experienced leadership and maritime capacity.” He highlighted the exercise's role in safeguarding sea lines of communication and protecting critical infrastructure. Rear Admiral Johan Norlén stated, “By sharing our knowledge and experience of underwater warfare in the unique conditions of the Baltic Sea region, we increase the security and stability, make NATO stronger and address the security challenges of today.”
Conclusion
As NATO conducts the Playbook Merlin 25 exercise, the alliance is not only enhancing its anti-submarine warfare capabilities but also reinforcing its collective defense posture in the Baltic Sea. The integration of Sweden into NATO's maritime strategy marks a significant evolution in regional security dynamics, with the potential to deter threats from adversaries, particularly Russia, in this strategically vital area.