Key Takeaways from the ISW : Russian forces in April 2026 suffered a net loss of territory controlled in the Ukrainian theater for the first time since Ukraine’s August 2024 incursion into Kursk Oblast. The relative decline in the rate of Russian advances may be related in part to annual seasonal patterns. The rate of Russian advances has slowed in 2026 compared to 2025, but the changing character of the war, particularly Russia’s increased use of infiltration tactics over the course of 2025,