The Line of Actual Control (LAC), the 4,057-kilometer boundary that runs between China and India along the arc of the world's highest mountains, has caused its share of strife. Over the years, the LAC has sparked standoffs, skirmishes and war between the two expanding nuclear powers. To try to keep the peace, Beijing and New Delhi began a dialogue in 2003 called the Special Representatives Meeting on the India-China Boundary Question. Yet 19 rounds of talks later, China and India still disagree on the location of the border between them — and over which side rightfully controls the territories of Aksai Chin and Arunachal Pradesh.

Despite their enduring differences, India and China largely have managed to keep their border disputes from spilling over into other aspects of their relationship, such as trade. But that may start to change. As China forges deeper ties with India's nuclear archrival, Pakistan, and as each side of the LAC tries to emphasize its sovereignty along the contested border, New Delhi and Beijing could have a harder time avoiding conflict.

A Wolf in Sheep's Clothing?

For Beijing, control of Arunachal Pradesh boils down to a matter of national security. One of China's main geopolitical imperatives is to secure a buffer on its western flank that, along with the Pacific Ocean on the east, would protect its densely populated core territory. Annexing the Kingdom of Tibet in 1950 enabled Beijing to realize that goal, so long as it could maintain control over its western buffer by thwarting challenges to its sovereignty. The Dalai Lama presented one such challenge. The prominent monk participated in a failed uprising against Beijing in March 1959. (His role in the revolt doubtless is one of the reasons the Chinese government views the Dalai Lama not as a spiritual figure but as a separatist whom it often describes as a "wolf in sheep's clothing.") After that, he fled to India — the birthplace of Buddhism, no less — where he received a warm welcome.

The Dalai Lama's presence was a boon for India. Hosting the exiled religious leader, for example, enabled New Delhi to draw international attention to the issue of Tibetan sovereignty, a tactic it still uses today. But India's support for the Dalai Lama vexed China, all the more so because New Delhi has long held control of Arunachal Pradesh and, with it, the strategic town of Tawang. As an important site in Tibetan Buddhism, Tawang represents an essential piece of China's strategy to assert its sovereignty over Tibet. Beijing often cites the town's significance in Tibetan Buddhism to support its claim to Tawang, and it probably won't give up its quest for control of the town anytime soon. China, in fact, may be disputing India's claim to Arunachal Pradesh, a territory Beijing would likely struggle to control, as a bargaining tactic to secure Tawang. Yet considering that relinquishing the town would give China greater access to India's vulnerable Siliguri corridor, New Delhi would hardly entertain the idea.

Kashmir: The Crown of India

Along the Western reaches of the LAC, India has its own bone to pick with China in the 38,000-square kilometer territory of Aksai Chin. New Delhi claims the area as part of Kashmir, a region whose control it has contested with Pakistan, as well, ever since the Partition of 1947. Today, India's authority in Kashmir extends to the regions of Jammu, Kashmir and Ladakh, collectively known as Jammu and Kashmir, while Pakistan administers two other constituent territories, Azad Kashmir and Gilgit-Baltistan. (New Delhi also claims another territory, the Trans-Karakoram Tract, which Islamabad ceded to Beijing in 1963.) Recognizing China's authority over Aksai Chin is a dangerous prospect for the Indian government, since doing so could signal to Pakistan that New Delhi's claims to its portion of Kashmir were similarly negotiable. In response, Islamabad could increase the military pressure on New Delhi along the Line of Control, where India and Pakistan have been fighting intermittently for decades. 

And Pakistan isn't the only factor preventing New Delhi from making a compromise in Aksai Chin. Renouncing India's claims to the region could come at a prohibitive cost for Prime Minister Narendra Modi's political career. Members of the opposition and of the ruling Bharatiya Janata Party alike would condemn the action as appeasement, a sign of weakness when India is trying to establish itself as a rising global power. The country, after all, is trying to exercise greater sovereignty in its border regions by building 73 new strategic roads to serve them. At the same time, China probably won't yield to India's demands over Aksai Chin, since it knows Pakistan would oppose the gesture and since a vital road, the G219 highway, runs through the region. Beijing would give New Delhi a portion of Aksai Chin at most as part of a border negotiation.

Succession, Not Secession

Because each side administers a territory that the other claims, compromise is the only solution to the dispute along the LAC. But neither Beijing nor New Delhi has much leeway to meet the other's demands. The situation likely will become even more tense as succession looms for the 81-year-old Dalai Lama. China has promised to observe the Tibetan Buddhist traditions to find a successor, which dictate that the reincarnated Dalai Lama must be born in Tibetan territory and approved by the central government. The process could come back to haunt Beijing if the 15th Dalai Lama is born in Tawang, thereby further shifting the spiritual center of gravity in Tibetan Buddhism to India. To try to weaken Beijing's power over his successor, meanwhile, the Dalai Lama has hinted that he may opt for emanation — that is, choosing the next Dalai Lama himself — rather than reincarnation.

In the meantime, relations between India and China seem to be entering a more contentious phase. Beijing continues to test its neighbors' limits and military responsiveness by asserting control over disputed territories, including those in the South China Sea and the Doklam Plateau, more and more brazenly. As China looks to hone its own military response, it may temporarily suspend its infrastructure projects as it has in the past. But once it resumes construction on these ventures — such as the road it was trying to extend through Doklam when its latest standoff with India began — China will provoke another confrontation. And the growing nationalist movements in both countries suggest that the next border dispute is not a question of if but of when.