Indo-Pakistani War (1971) prisoners of war

At the close of the Indo-Pakistani War of 1971 on December 16th, 1971, the Pakistani Army forces signed an instrument of surrender resulting in the surrender of 90,000 Pakistani troops to the Indian army. This surrender of troops was the largest the world had seen since World War II. India’s taking of 90,000 Pakistani POWs directly contributed to the recognition of Bangladesh’s sovereignty as India used this action as a tool to coerce Pakistan and then eventually other nations to recognize Bangladesh’s sovereignty and independence, which also had the effect of increasing India's national security by removing a hostile Pakistani-controlled state from India's eastern border. The POWss release was conditional to not only Pakistan’s acceptance of Bangladesh’s independence but also that of other nations including Bhutan, USA, USSR, and China. By holding these 90,000 Pakistani prisoners of war, India gained itself a bargaining chip to aid in establishing Bangladesh’s sovereignty.

Custody
India treated all the POWs in strict accordance with the Geneva Convention, rule 1925. These 90,000 POWs were slowly released by India in a six-month duration following the end of the war on December 16th, 1971. The POWs were not released until Pakistan agreed to sign the Simla Agreement. The Simla Agreement treaty ensured that Pakistan recognized the independence of Bangladesh in exchange for the return of the Pakistani POWs.

Foreign relations impact
The foreign reaction to India’s taking of these 90,000 POWs varied from nation to nation. The United Nations supported India’s move as they condemned the human rights violations the Pakistani Armed Forces inflicted upon Bangladeshis. As a result the U.N. was quick to accept Bangladesh’s independence. Bhutan became the second country after India to recognize Bangladesh’s independence and did so with no issues. The United States however, was an ally of Pakistan both materially and politically, and as a result they did not support India’s taking of 90,000 Pakistani POWs. The U.S. saw India’s actions as threatening especially since India had just became a nuclear power and maintained close military ties with the U.S.S.R. The Soviet Union supported both the armies of Bangladesh and India and thus supported Bangladesh’s unwaveringly. As a result of Soviet support, all nations that were part of the Warsaw Pact also recognized Bangladesh’s independence. Soviet backing ensured that the states in the U.S.S.R.’s sphere of influence, including Albania, Bulgaria, Czechoslovak Socialist Republic, Germany, Hungary, Poland, and Romania all recognized Bangladesh’s independence. China, despite being a communist nation, was also an ally of Pakistan and did not support the measures India took to have Bangladeshi sovereignty recognized. China even went as far as vetoing Bangladesh’s application to become a member of the United Nations and was one of the last nations in the world to recognize Bangladeshi independence, not doing so until August 31st, 1975.