Submitted via IRC for TheMightyBuzzard
For 15 years, Sweden believed Russian submarines were invading their territory. The disturbances that were detected in the ocean led to some tense times and almost brought the countries to the brink of war, but in actuality, they were just Herring farts.
Source: https://notthebee.com/article/fish-farts-almost-caused-a-diplomatic-crisis-for-sweden [notthebee.com]