The Sino-Indian War was an armed conflict between China and India that occurred from October to November 1962. This war was essentially an escalation of the ongoing border dispute between the two nations. The primary areas of conflict were along the border regions: in India's North-East Frontier Agency to the east of Bhutan and in Aksai Chin to the west of Nepal.

Tensions between China and India had been escalating following the 1959 Tibetan uprising, after which India granted asylum to the Dalai Lama. The situation worsened as India refused China's diplomatic settlement proposals between 1960 and 1962. China responded by resuming "forward patrols" in the Ladakh region, which it had previously ceased.^[38] The conflict intensified amidst the global tension of the Cuban Missile Crisis, with China abandoning all efforts for a peaceful resolution on October 20, 1962. This led to Chinese forces invading disputed territories along the 3,225-kilometer (2,004 miles) border in Ladakh and across the McMahon Line in the northeastern frontier.

The Chinese military pushed Indian forces back, capturing all the territory they claimed in the western theater and the Tawang Tract in the eastern theater. The conflict ended when China declared a ceasefire on November 20, 1962, and announced its withdrawal to its pre-war positions, essentially the Line of Actual Control, which served as the effective China–India border. The war was characterized by mountain warfare, conducted at altitudes over 4,000 meters (13,000 feet), and was limited to land engagements, with neither side using naval or air assets.

During this period, the Sino-Soviet split influenced international relations significantly. The Soviet Union supported India, notably through the sale of advanced MiG fighter aircraft. Conversely, the United States and the United Kingdom declined to sell advanced weaponry to India, leading India to rely more on the Soviet Union for military support.^[39]