NEW DELHI ― This month marks the 50th anniversary of China’s military attack on India, the only foreign war that communist-ruled China has won. Yet that war failed to resolve the disputes between the world’s two most populous countries, and its legacy continues to weigh down the bilateral relationship. While their economic heft is drawing increasing international attention, their underlying strategic rivalry over issues ranging from land and water to geopolitical influence in other regions usually attracts less notice.

The international importance of the China-India relationship reflects the fact that together they account for 37 percent of humanity. Although they represent markedly different cultures and competing models of development, they share a historical similarity that helps shape both countries’ diplomacy: each freed itself from colonial powers around the same time.

Throughout their histories, the Indian and Chinese civilizations were separated by the vast Tibetan plateau, limiting their interaction to sporadic cultural and religious contacts; political relations were absent. It was only after China’s annexation of Tibet in 1950-1951 that Han Chinese troops appeared for the first time on India’s Himalayan frontiers.

Just over a decade later, China surprised India’s ill-prepared army by launching a multi-pronged attack across the Himalayas on October 20, 1962. Chinese Premier Zhou Enlai publicly said that the war was intended “to teach India a lesson.”

Taking an enemy by surprise confers a significant tactical advantage in war, and the invasion inflicted an immense psychological and political shock on India that greatly magnified the initial military advances that China achieved. China’s blitzkrieg created a defeatist mindset in India, forcing its army to retreat to defensive positions. India, fearing unknown consequences, even shied away from employing its air power, although the Chinese military lacked effective air cover for its advancing forces.

After more than a month of fighting, China declared a unilateral ceasefire from a position of strength, having seized Indian territory. The Chinese simultaneously announced that they would begin withdrawing their forces on Dec. 1, 1962, vacating their territorial gains in the eastern sector (where the borders of India, Myanmar, Tibet, and Bhutan converge) but retaining the areas seized in the western sector (in the original princely state of Jammu and Kashmir). These withdrawal parameters meshed with China’s pre-war aims.

Just as Mao Zedong started his invasion of Tibet while the world was preoccupied with the Korean War, so he chose a perfect time to invade India, as recommended by the ancient strategist Sun Tzu. The attack coincided with a major international crisis that brought the United States and the Soviet Union within a whisker of nuclear war over the stealthy deployment of Soviet missiles in Cuba. China’s unilateral ceasefire coincided with America’s formal termination of its naval blockade of Cuba, marking the end of the missile crisis.

Mao’s shrewd timing ensured India’s isolation from sources of international support. Throughout the invasion, the international spotlight was on the potential US-Soviet nuclear showdown, not on the bloody war raging in the Himalayan foothills.

India’s humiliating rout hastened the death of its prime minister, Jawaharlal Nehru; but it also set in motion the country’s military modernization and political rise.

Fifty years later, tensions between India and China are rising again amid an intense geopolitical rivalry. Their entire 4,057-kilometer border ― one of the longest in the world ― remains in dispute, without a clearly defined line of control in the Himalayas.

This situation has persisted despite regular Chinese-Indian talks since 1981. In fact, these talks constitute the longest and most futile negotiating process between any two countries in modern history. During a 2010 visit to New Delhi, Chinese Premier Wen Jiabao stated bluntly that sorting out the border disputes “will take a fairly long period of time.” If so, what does China (or India) gain by continuing the negotiations?

As old wounds fester, new issues have begun roiling bilateral relations. For example, since 2006 China has initiated a new territorial dispute by claiming the eastern sector (the Austria-size Arunachal Pradesh state), from which its forces withdrew in 1962, describing it as “Southern Tibet.”

A perceptible hardening of China’s stance toward India since then is also reflected in other developments, including Chinese strategic projects and the country’s military presence in the Pakistani-held portion of Kashmir, a region where the disputed borders of India, China, and Pakistan converge.

Indian defense officials have reported increased military incursions by Chinese troops in recent years. In response, India has been beefing up its military deployments along the border to prevent any Chinese land grab. It has also launched a crash program to improve its logistical capabilities by constructing new roads, airstrips, and advanced landing stations along the Himalayas.

The larger strategic rivalry between the world’s largest autocracy and its biggest democracy has also sharpened, despite their fast-rising trade. In the past decade, bilateral trade has risen more than 20-fold, to $73.9 billion, making it the only area in which bilateral relations have thrived.

Far from helping to turn the page on old disputes, this commerce has been accompanied by greater Sino-Indian geopolitical rivalry and military tension. Booming bilateral trade is no guarantee of moderation between countries.

Although China set out to teach India a “lesson,” the 1962 war failed to achieve any lasting political objectives and only embittered bilateral relations. The same lesson is applicable to the Sino-Vietnamese context: In 1979, China replicated the 1962 model by launching a surprise blitzkrieg against Vietnam that Chinese leader Deng Xiaoping admitted was designed to “teach a lesson.” After 29 days, China ended its invasion, claiming that Vietnam had been sufficiently chastised. But the lesson that Deng seems to have drawn from the PLA’s poor performance against Vietnam is that China, like India, needed to modernize every aspect of its society.

By Brahma Chellaney

Brahma Chellaney, professor of strategic studies at the New Delhi-based Center for Policy Research, is the author of “Asian Juggernaut and Water: Asia’s New Battleground.” ― Ed.

(Project Syndicate)