In early 2022, Ukrainian forces did something seemingly unusual. They blew up one of their own dams on the Irpin River, just north of Kyiv, inundating hundreds of hectares of surrounding floodplains, and submerging villages in the process.  

That newly formed wetland became an impenetrable barrier, stopping Russian forces in their tracks and saving the capital from capture.  

Now, two countries along NATO's eastern borders are weighing wetlands as a frontline defense amid fears of a potential Russian invasion. Poland and Finland are considering re-flooding drained peatlands — like moors and swamps — to serve as natural barriers. 

The approach could also benefit the climate. Though they cover just 3% of Earth's land surface, healthy, wet peatlands lock carbon underground, storing twice as much CO2 as forests. But over time, large swathes of the EU's bogs, moorland and swamp have been drained for agriculture. 

As a result, their storage capacity is lost. Around 7% of the EU's greenhouse gas emissions come from drained peat soils and former wetlands. So, restoring them is essential for achieving the bloc's climate goals. 

How peatlands in Finland are expected to strengthen defense capabilities

Finland's government is currently trying to pinpoint suitable areas to rewet in the east of the country, close to the Russian border. The focus is on peatlands, wetlands, and forests with deadwood that form natural barriers.

"Restored bogs may serve as natural obstacles, potentially limiting the movement of military equipment and enhancing Finland's defensive capabilities," Finland's Ministry of the Environment told DW in a written statement. It is currently setting up a working group to evaluate specific plans and assess the scope of renaturation for defense purposes. 

While simultaneously strengthening biodiversity, reducing emissions, and promoting air and water quality. The departments of defense and agriculture are also a part of the working group. 

As well as supporting national security, restored areas could be used for recreation and leisure activities, the ministry added.

Swamps for defense: a centuries-old idea

Peatlands, mud, and wetlands have long been part of war and defense strategies. 

In the 1500s, farmers in northern Germany used their knowledge of local moorlands to get the better of the Danish army. Likewise, impassable swamps played a key role in the defeat of Napoleon Bonaparte's French army during the Russian campaign of 1812, and bogs and peatlands were major obstacles for German and Allied troops in both World War I and II.

"There is no military equipment that can simply drive through a wet peatland," said Franziska Tanneberger, head of the Greifswald Moor Centrum, a collaboration between the University of Greifswald and the Michael Succow Foundation.

The center estimates that an investment of €250 to €500 million ($290 - $581 million) could see around 100,000 hectares of Europe's peatlands and swamp revived and rewetted.

Tanneberger says peatlands filter and store water in increasingly dry and hot years and store large amounts of climate-damaging carbon dioxide. And they "do it for free, if we let them." 

Poland's "East Shield” initiative – forests and swamps as protective barriers

Poland also wants to significantly reinforce its eastern flank along the border with Belarus and Russia. Its "East Shield" project is aiming to deter a potential attack through the expansion of surveillance and infrastructure, and the creation of physical barriers by 2028. 

"The natural environment in the border areas is an obvious ally of any actions enhancing the elements of Eastern Shield," Poland's Ministry of Defense told DW in a written statement.

This includes rewetting peatlands and reforesting border areas.  

"In this instance, environmental and defensive aims overlap," the ministry's statement said. "Potential engineering works will be conducted in those places where natural barriers will prove to be an insufficient obstacle."

Germany's role as a NATO hub

Germany is not currently planning to restore peatlands for defense purposes, according to the country's Defense Ministry. 

In NATO's defense plan, Germany is considered a "hub," meaning it is an important transit country for troop movement within the alliance.

Because swamps and peatlands have a direct impact on the mobility of both enemy and friendly units, rewetting could have both advantages and disadvantages for defending troops, the ministry told DW.

Currently, the disadvantages outweigh the advantages for Germany's armed forces, according to the ministry. 

This article was originally published in German..