Wetlands, forests, peatlands, and mangrove swamps support native biodiversity and sock away large amounts of carbon. They also bog down invading armies, history shows.
These are the facts behind a new national security strategy concept that researchers from the University of East London call “defensive rewilding.” The idea is that large-scale ecosystem restoration can help protect a country’s borders – deterring invasions, slowing enemy advances, and funneling adversaries into more easily defended corridors.
Climate action and national defense are often cast as competitors for the same limited pot of government funds. But in fact, ecosystem restoration can contribute to both aims, the researchers say.
Take peatlands, for example: they’re unparalleled at storing carbon. And absolutely terrible at holding up heavy-duty military vehicles.
Or dense, mixed-species natural forests: great for biodiversity, and also for hiding defenders from surveillance drones and loitering munitions.
Natural rivers with restored floodplains provide flood control and support aquatic life and fisheries. As a bonus, their banks are too soft and their channels too wide for military tactical bridges.
The Pripyat marshes along the present-day Ukraine-Belarus border were a major barrier to German advances during Operation Barbarossa in 1941. Also during World War II, coral reefs and mangrove ecosystems frustrated amphibious invasions throughout the Pacific theater. More recently, Ukraine’s flooding of the Irpin River floodplain in 2022 was a major factor in stopping the Russian advance on Kyiv.
The latter example did not involve established wetlands, but still illustrates the concept, the researchers say. They define defensive rewilding as “the intentional, pre- or mid-conflict enhancement and restoration of ecosystems to create militarily advantageous terrain, while concurrently delivering significant environmental benefits.”
Defensive rewilding is not restoration as part of post-conflict nation-building, and it’s not mid-conflict environmental destruction for military advantage (known as WarWilding, like Saddam Hussein’s draining of the Mesopotamian marshes).
Rewilded ecosystems can function as a form of “deterrence by denial” – the enemy takes a look at how an invasion is likely to go, and decides to pass. Another plus is that it is “inherently defensive,” the researchers say: there’s no mistaking wetland restoration for saber-rattling, so rewilding can improve a country’s strategic situation without risking touching off a regional arms race.
Ecosystem restoration is often cheaper than constructing conventional defensive fortifications like anti-tank ditches – and rewilded ecosystems last longer and require little maintenance to boot. However, the researchers note, the ecosystem restoration has to be large-scale to really pose a deterrent.
Rewilding isn’t a national defense strategy on its own. It still takes good intelligence and solid strategy to prevent and repel invasions, and modern military technology means that natural obstacles will sometimes only slow enemy advances rather than stopping them entirely. The same wild landscapes that bog down invaders can frustrate counteroffensives, and ecosystems can be damaged in the crossfire.
Still, defensive rewilding represents a novel way of thinking and a potential win-win approach, the researchers argue. “From a fiscal perspective, this represents a shift from ‘spending’ on defense to ‘investing’ in resilience,” they write.
Source: Jelliman S. et al. “Defensive Rewilding: a Nature-Based Solution for National Security.” The RUSI Journal 2026.
Image: ©Anthropocene Magazine
