NATO’S ASW LESSONS: A CONVERSATION WITH REAR ADM. BRETT GRABBE

Defence Turkey:  During the Cold War, anti-submarine warfare was considered vital to NATO’s survival. Afterward, many analysts argued that navies allowed ASW expertise to decline. Compared with those peak Cold War years, is NATO relearning forgotten lessons today, or learning entirely new ones?

GRABBE: Fortunately, within NATO’s submarine community we never really forgot the importance of anti-submarine warfare. Exercises such as Dynamic Mongoose and Dynamic Manta have continued for many years specifically as practice and lesson-learning events. Those exercises allowed us to maintain continuity even when global attention shifted elsewhere.

We have also expanded our training framework. The addition of Dynamic Merlin in the Baltic followed Sweden and Finland joining NATO, which has fundamentally changed that region operationally. The Baltic is now largely a NATO-controlled maritime space where we can train extensively and refine our procedures.

So, from our perspective, this is not relearning from scratch. We have maintained a strong undersea capability and an institutional process for capturing lessons learned. What we are doing now is building on that foundation rather than rebuilding it.

Defence Turkey: Traditionally, ASW has always been conducted against manned submarines. With unmanned underwater systems emerging, do NATO’s core assumptions about ASW need to change?

GRABBE: NATO approaches this from a defensive standpoint, and unmanned technology presents an opportunity rather than a disruption. Manned platforms have advanced tremendously over the past decades, but they have also become increasingly expensive to build and operate.

Uncrewed systems offer ways to complement those manned capabilities. They can take on certain tasks, expand coverage, and work alongside traditional platforms. That partnership between manned and unmanned systems is where we see the future heading, and it aligns with guidance from NATO Maritime Command.

The fundamentals of ASW remain valid, but the toolkit is expanding.

Defence Turkey:  Are NATO forces technologically and conceptually ready to confront future adversary underwater systems?

GRABBE: Individually, NATO nations possess significant capability and expertise. The real strength comes from bringing those capabilities together. Major exercises — for example Dynamic Messenger held in Portugal last year — allow us to integrate national systems into a collective operational framework.

We have seen substantial progress in unmanned aerial and surface systems. Unmanned undersea technologies have developed more slowly, and we recognize that additional effort and investment are required in this area.

However, when you consider the combined industrial and military capacity of 32 allied nations, I have a very high level of confidence that NATO will continue to maintain situational awareness and retain the advantage below the waterline.

Defence Turkey:  For NATO to stay ahead in ASW, what matters more: more sensors and nodes, or better processing and analysis of data?

GRABBE: That is a challenging question. From my perspective, the most important factor is how effectively we use the resources already available to us. Whether that ultimately means more sensors, more nodes, or more computing capability is not for me alone to determine.

My daily responsibility is ensuring that the capabilities nations provide are employed together in the most efficient and effective way possible. Integration and coordination are ultimately what generate operational advantage.

Defence Turkey:  Submarine operations inherently depend on stealth. Yet maintaining theatre-wide awareness requires communication, which risks detection. How does NATO balance this dilemma?

GRABBE: Submariners, regardless of nationality, are very practiced at being covert — that is fundamentally what we do. Within NATO operations, we generally do not expect continuous two-way communication with submarines.

Instead, we primarily send information for them to receive and maintain situational awareness. When operationally feasible, submarines may transmit reports back, but by design we assume communication is largely one-way.

This mirrors how nations operate their submarines nationally, so applying the same approach within NATO is natural and effective.

Defence Turkey: You command submarines from fourteen NATO nations, each with its own traditions and operational culture. What is the biggest challenge in creating a coherent multinational submarine force?

GRABBE: I benefit greatly from the work done by my predecessors. Integration happens continuously, not only during exercises like Dynamic Manta, Mongoose, or Merlin, but throughout the year.

Each of the fourteen submarine nations assigns representatives — many of them former submarine commanding officers — to NATO Maritime Command in Northwood. We work side-by-side every day. These officers serve as bridges between national commands and NATO structures.

As a result, when a nation transfers a submarine under NATO operational control, we already understand each other’s procedures and expectations. The personnel assigned are highly experienced professionals capable of translating both operationally and culturally between national and alliance perspectives.

Defence Turkey:  NATO submarine operations span very different environments — the Mediterranean, Baltic, and North Sea. Which theatre concerns you most?

GRABBE: It is a bit like asking a parent to choose a favorite child — you really cannot. Each area of responsibility has unique characteristics. Some regions feature choke points, others shallow waters, and others deep operating areas. Each environment presents both challenges and advantages.

Because NATO conducts exercise regularly in all three regions, I believe we remain well prepared across the full spectrum of operating environments.

Defence Turkey: Finally, from your perspective, what does Dynamic Manta represent for NATO today?

GRABBE: Exercises like Dynamic Manta demonstrate how alliance nations train together, integrate capabilities, and continuously refine undersea warfare skills. They ensure that when nations operate together operationally, they already share understanding, procedures, and confidence.

That preparation is what ultimately allows NATO to maintain effectiveness beneath the surface