As Asia returns to wealth and power, all eyes are on China and India, the two most populous nations on the Earth, with burgeoning economies and geopolitical clout. Within India, China watchers are a growing tribe analyzing and debating the rise of China and its implications.

How will these two countries relate to each other in the coming years? In a changing world order, will the US team up with India to balance the growing might of China? The answers, however, are not monochrome.

Traditionally, security experts have looked at the two Asian countries through the prism of the past, the long and simmering border dispute, and through the many misgivings that significant sections of each country harbor about the other nation.

By calling the relationship between India and the US "the defining partnership of the 21st century" during his recent visit to India, US President Barack Obama bolstered the theory of India as a counterweight to an assertive China.

Given the baggage of the past, it is also not surprising that in the run-up to Chinese Premier Wen Jiabao's visit to New Delhi in mid-December, the "boundary dispute" between the two countries is once again a topic of discussion in New Delhi. India and China held the 14th round of boundary talks in Beijing at the end of November.

Differences of perception over the boundary question is not the only area of concern. There was widespread disquiet in India when, on November 12, China started diverting the water of the Yarlung Zangbo River in Tibet for a hydroelectric project.

The river, called the Brahmaputra in South Asia, is the lifeline of northeastern India and northern Bangladesh, so any reduction in the volume of water it carries from its upstream is of concern to India.

The Chinese government hastened to assure the Indians that they were not impounding any water but merely channeling it for a distance to generate electricity. But the initial report by the Xinhua News Agency said it would also "help in irrigation and flood control." Indian hydrology experts pointed out that this cannot be done without holding back at least some of the water.