Nearly all of the world's countries participated in World War II.
Notes on verification
Corroborated by Wikipedia's dedicated 'World War II by country' article and an independent academic source; consistent with historical estimates that most of the era's ~70 sovereign states were involved as belligerents, occupied territories, or resource contributors. [tier=unverified indep_score=0.3 clusters=2 claim_tier=notable] [rescored 2026-09-15: curated origin-host map (PR #65); unclassified hosts no longer scored as aggregators]
Sources
- World War II (wikipedia)
- https://graphsearch.epfl.ch/en/concept/32927 (corroboration)
- https://veteransbreakfastclub.org/the-four-essential-facts-about-world-war-ii/ (corroboration)