They both have lots of nuclear weapons--for starters.
How to Kills Billions of People: If China and India Went to War
The war on the ground between the Indian and Chinese armies might at first glance seem like the most decisive phase of the war, but it’s actually quite the opposite. Both the western and eastern theaters are in rugged locations with little transportation infrastructure, making it difficult to send a mechanized army through.
A hypothetical war between India and China would be one of the largest and most destructive conflicts in Asia. A war between the two powers would rock the Indo-Pacific region, cause thousands of casualties on both sides and take a significant toll on the global economy. Geography and demographics would play a unique role, limiting the war’s scope and ultimately the conditions of victory.
(This article originally appeared in 2017.)
India and China border one another in two locations, northern India/western China and eastern India/southern China, with territorial disputes in both areas. China attacked both theaters in October 1962, starting a monthlong war that resulted in minor Chinese gains on the ground.
Both countries’ “No First Use” policies regarding nuclear weapons make the outbreak of nuclear war very unlikely. Both countries have such large populations, each over 1.3 billion, that they are essentially unconquerable. Like all modern wars, a war between India and China would be fought over land, sea, and air; geography would limit the scope of the land conflict, while it would be the air conflict, fought with both aircraft and missiles, that would do the most damage to both countries. The trump card, however, may be India’s unique position to dominate a sea conflict, with dire consequences for the Chinese economy.