Wetlands and radioactive soil: How Ukraine’s geography could influence a Russian invasion

As military analysts warn of a possible Russian invasion of Ukraine, they also are keeping an eye on the weather. Temperatures, cloud cover or even the radioactivity in the soil could determine when and where Russian troops make a possible move.

For centuries, armies and nations have waged wars on these same lands, from the steppes to the Eastern European heartland, and have faced similar obstacles — from mucky wetlands to rushing rivers and treacherous mountain ranges.

Russia, while mobilizing more than 100,000 troops along the Ukraine border, denies it plans to invade. But Washington and its allies are preparing for possible aggression by sending military personnel and equipment to NATO members near Ukraine.

Now, with airstrike capabilities and state-of-the-art materiel on both sides, geography and weather are less of a factor than they were in the past. But they still could influence the timing and the tide of a potential conflict. Cold weather provides hard, fast terrain countrywide for an invasion, experts said. Warmer weather starting in later February and into March brings with it thawing grounds, leading to muddy conditions that are less than ideal for heavy military vehicles.

“It is very inconvenient to carry out offensive operations in the spring,” said Kirill Mikhailov, an analyst at the Conflict Intelligence Team, an independent Russian open-source investigative organization that monitors Russia’s military. “Because the thaw turns ravines into creeks, and creeks into rivers. If you carry out an operation, it should be carried out either in January or February.”

The Pinsk Marshes

To Ukraine’s north span roughly 100,000 square miles of wetlands known as the Pinsk Marshes. Here is one place the cold could really play a role. During the winter, these mucky flatlands freeze over, providing a more stable terrain for heavy military vehicles that would otherwise get stuck in the mud.

Experts say the frozen ground, usually present in February, could provide Russian troops with the best window to cross into Ukraine. While more roads have recently been built throughout the marshes, traversing the open terrain would be strategically important.

“Those fields become critical because you can’t risk bottlenecks on a roadway,” said Seth G. Jones, senior vice president at the Center for Strategic and International Studies (CSIS). “You run into real problems on very muddy terrain in the March-April time frame.”

Historically the marshes have been an obstacle to forces. But muddy landscape might not be a deciding factor this time around, according to a written analysis by the Center for Naval Analyses Russia Studies Program (CNA) in response to questions from The Washington Post. “While these marshes were flagged as a potential hazard for Western forces fighting a hypothetical war in the U.S.S.R. and considered ‘impassible except during winter,’ Russian troops have long proved quite adept at handling marsh and swamp terrain.”

During World War II, the marshes posed a challenge to German forces invading during Operation Barbarossa.

Belarusian Border

The marshes are spread across another key strategic location: the Belarusian border. As the ground freezes, it could give Russian troops access to Kyiv, which falls a mere 56 miles to the south, though that most-direct route passes through the nuclear disaster site of Chernobyl.

Russia has begun mobilizing forces ahead of joint Belarus-Russian military exercises, scheduled to take place Feb. 10 to Feb. 20. CNA said Russia has sent more than 10 battalion tactical groups to Belarus, as well as naval and airborne units.

Belarusian President Alexander Lukashenko, a close ally of Russian President Vladimir Putin, has vowed to defend his country and Russia against Ukrainian “aggression.”

‘The Zone’

Russian forces seeking the most direct route to Kyiv could run into another obstacle: Chernobyl. The site of a nuclear disaster in 1986, the 1,000-square-mile zone is heavily restricted to keep people safe from radioactivity still embedded in the ground.

In November, Ukraine deployed border guards to patrol the area as tensions with Russia and Belarus heightened. While certain areas are safe to occupy for some time, the explosions and artillery fire of warfare in the area could be dangerous.

“The delivery of air-to-surface munitions, artillery, mortar and multiple rocket-launcher fire in the Belarus-Ukraine border area could also disperse radioactive debris in the soil,” said Russian military analyst Pavel Felgenhauer.

The Dnieper River

While an invasion from Belarus’s south would be the most direct route to Ukraine’s capital, many expect potential Russian military aggression to also come from the northeast and east, where pro-Moscow separatists control Ukrainian territory in Donbas, and more than 100,000 Russian troops have amassed on the country’s border with Ukraine.

They could come through Kharkiv, Ukraine’s second-most-populous city. There are no geographic obstacles separating this eastern metropolis from Russia, making it a fast and prime target.

Moving west, any invading force would reach the banks of the Dnieper River, which symbolically divides Ukraine into east and west, beginning in Russia and flowing through Belarus and Ukraine into the Black Sea.

The waterway, home to critical infrastructure including dams, would be a key consideration in an invasion from Belarus or Russia.


In the southern city of Zaporizhzhya, for example, is the Dnieper Hydroelectric Station, a massive dam that also joins the banks of the river.

In World War II, Soviet leader Joseph Stalin’s secret police destroyed this dam to make the river harder for German forces to cross, killing civilians and flooding towns in the process. The dam has since been rebuilt, and experts note that Ukraine could repeat the tactic, this time to slow down a Russian invasion, washing out oncoming forces.

But Joseph S. Bermudez Jr., a senior fellow for imagery analysis at CSIS, cautioned that the move could again drown Ukrainian towns. “If they blew the dams they’d do as much damage to the Ukrainian population as they would a Russian invasion,” he said.

The Black Sea

In Ukraine’s south is the Black Sea, an important body of water that serves as the country’s shipping route with its connection to the Mediterranean. The Black Sea has been the site of numerous conflicts throughout history, including the Russo-Turkish wars, the Crimean War in the 1850s and World War II.

In 2014, Russia annexed Crimea, giving the country expanded access to the sea.

Now, CNA said: “The Russian Navy depends on transit through the Black Sea for supplying military presence in Syria and for rotating ships in and out of its Mediterranean squadron.”

Since 2014, the organization added, the Russian navy’s Black Sea Fleet has “expanded and modernized.” Twenty of its ships were recently “engaged in a major naval exercise in the Black Sea,” as part of a “large-scale naval exercise involving all Russian fleets.”

Other Western naval vessels enter the Black Sea periodically, but those that stray too close to Crimea often face brushes with Russian warships, as Moscow sees these moves as a direct challenge to its annexation of the peninsula.

The Kerch Strait

The Kerch Strait divides the Black Sea and the Sea of Azov, and could be another access point for Russia. In 2018, Russia opened a 12-mile-long, $4 billion bridge over the strait, directly linking Russia to Crimea. Ukraine and the West have called the bridge another illegal infringement on Kyiv’s sovereignty.

The Carpathian Mountains

A mountain range runs through Ukraine’s west, forming a natural barrier that stretches from Romania through Slovakia. The higher-ground vantage points of its peaks made them coveted territory in past conflicts. Russians battled Austro-Hungarian troops during the winter of 1915 in World War I, and soldiers froze in the snowy terrain.

But the mountains wouldn’t factor in a potential Russian invasion today, analysts said. There’s been no recent Russian military presence detected in that area.

About this story

Editing by Reem Akkad, Lauren Tierney and Brian Murphy. Design and development by Garland Potts. Copy editing by Stu Werner.

Sources: Elevation data is from OpenTopography. Land crop and forest data is from the Copernicus Global Land Service. Water bodies data is from the European Commission’s Global Surface Water Explorer. Data on military exercises is from Conflict Intelligence Team, and Belarusian Defense Ministry. Chernobyl Exclusion Zone boundaries are from Chernobyl Tour. Potential invasion paths are from the Center for Strategic and International Studies (CSIS).

Júlia Ledur is a graphics reporter covering foreign news at The Washington Post. Before joining The Post in 2021, she worked as a graphics editor at the COVID Tracking Project at the Atlantic. Previously, she was on the graphics team at Reuters, covering Latin American politics, the environment and social issues with data and visuals.
Ruby Mellen reports on foreign affairs for the Washington Post.
Laris Karklis has been working at the Washington Post since 2000.