The 1965 war began as a series of border flare-ups along undemarcated territory at the Rann of Kutch in the southeast in April and soon after along the cease-fire line in Kashmir. The Rann of Kutch conflict was resolved by mutual consent and British sponsorship and arbitration, but the Kashmir conflict proved more dangerous and widespread. In the early spring of 1965, UN observers and India reported increased activity by infiltrators from Pakistan into Indian-held Kashmir. In mid-1965 Pakistan sent guerrilla forces into the Indian part of Kashmir in the hope of stirring up a rebellion that would either oust the Indians or at least force the issue back onto the international agenda. Pakistani forces did not find as much support among the Kashmiri population as they had hoped, and no uprising by Kashmiris against India took place. Fighting spread, and by August India had retaken Pakistani-held positions in the north while Pakistan attacked in the Chamb sector in southwestern Kashmir in September. A process of escalation culminated in a full-scale Indian offensive toward Lahore on September 6. Fighting, frequently very bitter, continued until a UN-sponsored cease-fire took hold on September 23. Both sides had tacitly agreed not to let the war spread to the East Wing of Pakistan. Each country had limited objectives, and neither was economically capable of sustaining a long war because military supplies were cut to both countries by the United States and Britain.
The war was militarily inconclusive; each side held prisoners and some territory belonging to the other. Losses were relatively heavy--on the Pakistani side, twenty aircraft, 200 tanks, and 3,800 troops. Pakistan's army had been able to withstand Indian pressure, but a continuation of the fighting would only have led to further losses and ultimate defeat for Pakistan. Most Pakistanis, schooled in the belief of their own martial prowess, refused to accept the possibility of their country's military defeat by "Hindu India" and were, instead, quick to blame their failure to attain their military aims on what they considered to be the ineptitude of Ayub Khan and his government.The army was generally successful during the spring and summer of 1971 in restoring order in East Pakistan, but increasing Indian support of the antigovernment Bengali guerrillas known as the Mukti Bahini (Liberation Force) began to shift the balance. When Indian troops finally intervened directly in December, there was no hope of stopping them. On December 3, Pakistani forces began hostilities in the west with attacks on Indian airfields. They had little success, and within twenty-four hours India had seized air superiority, launched attacks against West Pakistan, and blockaded the coast. Pakistani forces in East Pakistan surrendered to the Indian army on December 16, and India offered a cease-fire. In the face of superior force on all fronts, Pakistan had little choice but to accept the breakup of the country and the independence of Bengalis in Bangladesh (the former East Pakistan).
There were periods of considerable tension between Pakistan and India in later years. In November 1986, India launched its largest maneuver ever, Operation Brass Tacks, menacingly close to the Pakistan border. The Pakistan Army responded with threatening countermovements, and in early 1987 there was serious concern that war might break out. India accused Pakistan of aiding Sikh insurgents in India's state of Punjab. Pakistan denied this accusation, but some people thought that Operation Brass Tacks might have been a means to strike at alleged bases in Pakistan's Punjab Province. The India-Pakistan hot line was brought into use, and Zia skillfully seized the initiative by traveling to India to view a cricket game, using the opportunity to meet with Indian leaders to defuse the situation.