THE disputed Sino-Indian border, long a source of intermittent clashes, is once again the focus of a confrontation in which Chinese and Indian troops are facing off - this time in an area claimed by Bhutan.

Interestingly, China's territorial claim to the contested area rests on an 1890 treaty, the Convention between Great Britain and China Relating to Sikkim and Tibet. At the time, Sikkim was a British protectorate and India was a British colony. Today, Sikkim is part of an independent India. A lot of water has flowed under the bridge, and yet China pins its claim on this relatively ancient treaty.

The latest conflict began after a construction party of the People's Liberation Army (PLA) entered the Doklam area and attempted to upgrade or extend a dirt road. An Indian account of the incident said: "It is our understanding that a Royal Bhutan Army patrol attempted to dissuade them from this unilateral activity." This was followed by the intervention of Indian troops, triggering a stand-off between Chinese and Indian troops, the first time on territory not claimed by India.