India retaliates following Pakistan's Operation Grand Slam which results in the Indo-Pakistani War of 1965 that ends in a stalemate followed by the signing of the Tashkent Declaration.

Operation Grand Slam was a key military operation of the Indo-Pakistani War of 1965. It refers to a plan drawn up by the Pakistan Army in May 1965, that consisted of an attack on the vital Akhnoor Bridge in Jammu and Kashmir, India. The bridge was not only the lifeline of an entire infantry division of the Indian Army, but could also be used to threaten the city of Jammu, an important logistical point for Indian forces. The operation saw initial success, but was aborted when the Indian Army opened a new front in the Pakistani province of Punjab in order to relieve pressure in Kashmir. This forced Pakistan to abandon Grand Slam and fight in Punjab, so that the operation ended in failure and stated objectives were not achieved.

The Indo-Pakistani war of 1965, also known as the second Kashmir war, was an armed conflict between Pakistan and India that took place from August 1965 to September 1965. The conflict began following Pakistan's unsuccessful Operation Gibraltar, which was designed to infiltrate forces into Jammu and Kashmir to precipitate an insurgency against Indian rule. The seventeen day war caused thousands of casualties on both sides and witnessed the largest engagement of armoured vehicles and the largest tank battle since World War II. Hostilities between the two countries ended after a ceasefire was declared through UNSC Resolution 211 following a diplomatic intervention by the Soviet Union and the United States, and the subsequent issuance of the Tashkent Declaration. Much of the war was fought by the countries' land forces in Kashmir and along the border between India and Pakistan. This war saw the largest amassing of troops in Kashmir since the Partition of India in 1947, a number that was overshadowed only during the 2001–2002 military standoff between India and Pakistan. Most of the battles were fought by opposing infantry and armoured units, with substantial backing from air forces, and naval operations.

The Tashkent Declaration was signed between India and Pakistan on 10 January 1966 to resolve the Indo-Pakistani War of 1965. Peace was achieved on 23 September through interventions by the Soviet Union and the United States, both of which pushed the two warring countries towards a ceasefire in an attempt to avoid any escalation that could draw in other powers.