Russia-Ukraine War — 2026-05-18

Russia Experiences First Sustained Net Loss of Ukrainian Territory Since October 2023

BLUFApril's territorial reversal is likely a brief accounting artifact rather than a turning point, and Russia is unlikely to post a second consecutive monthly net loss when ISW reports in mid-June.

The Economist, citing ISW data, reported this week that Ukraine has reclaimed approximately 189 square kilometers of Russian-held territory over the preceding 30 days, up from 113 square kilometers measured as of May 10, according to Seoul Economic Daily 1. The Economist also estimated Russian military deaths at between 280,000 and 518,000 as of May 12, with Russia sustaining 35,000 casualties monthly at a rate exceeding replacement recruitment 1. ISW assessed on May 16 that Russian Chief of General Staff Gerasimov made highly inaccurate battlefield claims for the fifth consecutive month, falsely asserting seizure of Borova and 85 percent of Lyman while ISW found Russian forces holding only about 14 percent of Kupyansk and fractional positions in other claimed towns 2.

Analysis
Russia is unlikely to record a second consecutive net loss of controlled Ukrainian territory in May, a judgment the mid-June ISW publication will test. April's reversal, per a single Seoul Economic Daily synthesis of ISW and AFP data without independent corroboration, rests on accounting excluding gray-zone areas. When those areas are included, Russia netted roughly 28 sq km that month; the structural advance has not halted. Post-rasputitsa conditions and elevated assault tempo in Donetsk support metric recovery through May. Russia's recruitment shortfalls and communication failures, predating the spring thaw, may instead mark structural degradation rather than a seasonal artifact. If May confirms a second loss, allied planners should recalibrate toward sustained Ukrainian offensive support.

2 sources

Russia Ukraine Territorial Gains Reverse for First Time Since October 2023 - Seoul Economic Daily
Russian Offensive Campaign Assessment, May 16, 2026 - Institute for the Study of War (ISW)