Indo-Pakistani War of 1971: Pakistan launches a pre-emptive strike against India and a full-scale war begins.

The Indo-Pakistani war of 1971, also known as the third Indo-Pakistani war, was a military confrontation between India and Pakistan that occurred during the Bangladesh Liberation War in East Pakistan from 3 December 1971 until the Pakistani capitulation in Dhaka on 16 December 1971. The war began with Pakistan's Operation Chengiz Khan, consisting of preemptive aerial strikes on eight Indian air stations. The strikes led to India declaring war on Pakistan, marking their entry into the war for East Pakistan's independence, on the side of Bengali nationalist forces. India's entry expanded the existing conflict with Indian and Pakistani forces engaging on both the eastern and western fronts.

Operation Chengiz Khan was the code name assigned to the preemptive strikes carried out by the Pakistani Air Force (PAF) on the forward airbases and radar installations of the Indian Air Force (IAF) on the evening of 3 December 1971, and marked the formal initiation of hostilities of the Indo-Pakistani War of 1971. The operation targeted 11 of India's airfields and also included artillery strikes on Indian positions in Kashmir. The targets were the Indian Airbases of Amritsar, Ambala, Agra, Awantipur, Bikaner, Halwara, Jodhpur, Jaisalmer, Pathankot, Bhuj, Srinagar and Uttarlai and air defence radars at Amritsar and Faridkot.