Here is my analysis of the claim:

Reasoning:

• The figure of 45 million is approximately accurate for Ukraine's population around 2014, before Russia's annexation of Crimea and the war in Donbas. According to Ukraine's Deputy Prime Minister, the population was 45 million before Russia's first invasion in 2014, and fell to 42 million after the annexation of Crimea¹.
• However, the claim that the population has fallen "to 25 million" is not accurate for the current population. The 25 million figure is a long-term demographic projection for 2051, not a current reality¹.
• Current estimates for Ukraine's population vary depending on whether occupied territories are included, but authoritative sources place the current population significantly higher than 25 million:
  • Wikipedia's demographic data estimates approximately 28.7 million for 2025 in government-controlled territory².
  • The UN's Worldometer estimates Ukraine's total population at approximately 37.9 million in 2024 and 39.5 million in 2026, though this methodology includes occupied territories³.
  • A Ukrainian demographer estimated the population in government-controlled territory at about 28 million at the beginning of 2026⁴.
• The Deputy Prime Minister of Ukraine stated in February 2025 that the population had dropped to around 32 million by the end of 2024¹.
• The 25.2 million figure cited in some reports refers to projections for 2051 by the Institute of Demography and Social Quality of Life at the National Academy of Sciences of Ukraine¹.
• The confusion may arise from conflating the population of government-controlled territory (which is lower) with Ukraine's total de jure population, and from mixing current statistics with future projections.

Overall validity: 35%

1. Ukraine's population stands at 32 million, says Deputy PM | Ukrainska Pravda
2. Demographics of Ukraine - Wikipedia
3. Ukraine Population (2026) - Worldometer
4. Depopulation and war threaten Ukraine's demographics - EDJNet