Right now India has not involved in China’s autonomous regions: Inner Mongolia, Xinjiang and Tibet. But, if push comes to the shove, India has the powers to foment trouble given a huge domestic Muslim and Buddhist population. India could also use its traditional links with Mongolia, Taiwan, Vietnam, Japan to encircle China in a covert war. Chinese society is precariously balanced especially when it comes to the non-Han minority and given all the economic tensions in the fast growing nation, it is easy to set the cat among the pigeons. In the same way, China could also do it in India, although with a little less success.

Nuclear factor: While Pakistan has less to worry about India’s nukes (nothing much to lose), China has everything to lose in a nuclear war with India. A cornered nation with nuclear power is the worst enemy you could have.

Thus, a Pakistan-China axis will never really work against India. The resulting mutual destruction is what preventing such an alliance from already happening.