3 December-17 December: India and Pakistan fight their second major war, over East Pakistan, which ends after 90,000 Pakistani troops surrender. The new nation of Bangladesh is created out of East Pakistan.
3 December – The Indo-Pakistani War of 1971 begins as Pakistan attacks 9 Indian airbases. The next day India launches a massive invasion of East Pakistan.
3 December-4 December night: The Indian navy destroyer INS Rajput sinks Pakistani submarinePNS Ghazi (former USS Diablo).