RESEARCH BRIEF
Understanding NATO’s Concept for
Deterrence and Defense of the
Euro-Atlantic Area
May 20, 2024 l Sean Monaghan, Katherine Kjellström Elgin, and Sara Bjerg Moller
NATO, the largest and most powerful military alliance in history, turned seventy-five in April. In July, the
leaders of NATO will return to the city where its founding document, the Washington Treaty, was signed in
1949. Most people have heard of NATO. Fewer know its most important document is the Strategic Concept,
which is updated every decade or so, and sets the Alliance’s strategy.
An even smaller group know about
NATO’s “Concept for Deterrence and Defence of the Euro-Atlantic Area.”
The DDA—or the “Deter and Defend” strategy, as it is known in alliance circles—is the centerpiece of NATO’s
dramatic “back to the future” transformation in recent years.
The DDA has helped the Alliance be more
forward-leaning in its defense and deterrence missions. For example, before Russia’s full-scale invasion of
Ukraine in 2022, several DDA measures were implemented to counter Russian attempts to destabilize Ukraine
and undermine Allied cohesion.
Since 2022, the DDA has been the linchpin in NATO’s efforts to deter Vladimir Putin from expanding his war
of aggression beyond Ukraine.
As NATO’s website explains, “The DDA Concept provides a single, coherent
framework for NATO Allies to contest, deter and defend against the Alliance’s main threats.”
Yet even for NATO watchers, the DDA is a puzzle in at least three ways. First, despite being “at the center of
the Alliance’s unprecedented post-Cold War” transformation, there was until recently little information about
it.
Second, the timing of the DDA was also strange, as it was agreed to two years before the Strategic Concept
it technically sits under.
Finally, the concept introduces a theory of success for deterring Russia that differs
from previous strategies in both method and timing.
NATO 2022 Strategic Concept (Brussels: NATO, 2022).
“Deter And Defend - An Overview,” NATO SHAPE Public Affairs Office, September 29, 2022, https://shape.nato.int/news-archive/2022/deter-and-defend-an-overview;
Sean Monaghan, “The Sword, the Shield, and the Hedgehog: Strengthening Deterrence in NATO’s New Strategic Concept,” War on the Rocks, August 23, 2022,
https://warontherocks.com/2022/08/the-sword-the-shield-and-the-hedgehog-strengthening-deterrence-in-natos-new-strategic-concept/.
Stephen R. Covington, “NATO’s Concept for Deterrence and Defence of the Euro-Atlantic Area (DDA),” Belfer Center for Science and International Affairs, Harvard
Kennedy School, August 2, 2023, https://www.belfercenter.org/publication/natos-concept-deterrence-and-defence-euro-atlantic-area-dda.
Covington, “NATO’s Concept for Deterrence and Defence of the Euro-Atlantic Area (DDA).”
“Deterrence and defence,” What we do, NATO, last updated October 10, 2023, https://www.nato.int/cps/en/natohq/topics_133127.htm.
Covington, “NATO’s Concept for Deterrence and Defence of the Euro-Atlantic Area (DDA).”
Both the DDA and the 2022 Strategic Concept were informed by the 2019 military strategy.
