As Ukrainian forces slowly push ahead with their 2023 counteroffensive after more than a year of shifting battle lines, the country's military and civilians face a deadly problem: land mines, potentially hundreds of thousands of them, scattered across roads, buried in fields and concealed in devastated cities.

There are new, advanced types that can sense movement or destroy vehicles from hundreds of meters away. Most common, however, are older, simple weapons that were produced in the tens of millions and fill the armories of both the Ukrainian and Russian militaries.

Reuters interviewed four humanitarian demining organizations and two military experts and examined technical surveys by mine-clearance groups of unexploded ordnance in Ukraine to reveal mine contamination so vast that it is most likely unprecedented in the 21st century.