The Indo–Soviet Treaty of Peace, Friendship and Cooperation was a treaty signed between India and the Soviet Union in August 1971 that specified mutual strategic cooperation. This was a deviation from India’s previous position of nonalignment during the Cold War.The Soviets moved into the Bay of Bengal with cruisers and destroyers and a submarine armed with nuclear missiles.
They tracked US Task Force 74 into the Indian Ocean from 18 December 1971 until 7 January 1972. The Soviets also had a nuclear submarine to help ward off the threat posed by USS Enterprise task force in the Indian Ocean.
The Soviet buildup on the Sino-Soviet border was a also a threat for China preventing any intervention from China.