Russian forces advanced 430 square kilometers (166 square miles) into Ukrainian territory in January and are headed towards the logistics hub of Pokrovsk, according to an AFP analysis of data from the US-based Institute for the Study of War (ISW).
This marks a slight slowdown compared to previous months, after a record advance of 725 square kilometres in November and 476 square kilometers in December.
More than 80 percent of Russia's advances in January took place in the Donetsk region, where Moscow's troops are trying to capture the key city of Pokrovsk.
The Russian army also advanced about 50 square kilometers on the northeastern front around the city of Kupiansk.
Moscow's advances in Ukraine had slowed during the previous two winters: In January 2023 it advanced 285 square kilometres, while in January 2024 it gained just 146 square kilometres.
Russia stepped up its offensive in the summer of 2024, while Ukraine made a large-scale operation toward the Russian city of Kursk, covering nearly 1,300 square kilometers in two weeks.
But the territory seized during Ukraine's advance shrank over the following months.
From 483 square kilometers on December 31, it further decreased by about 40 kilometers, extending over 442 square kilometres at the end of January.
AFP's calculations are based on files communicated daily by the ISW, which relies on information shared by both camps and satellite image analysis.