They pin down Indian troops and goad them into acts of oppression, no doubt. But meanwhile the fighters encourage the spread of Islamism in the Pakistani army. They also let the Taliban blackmail Pakistan over the presence of its paramilitary camps in Afghanistan. The support of foreign states also has its pitfalls. CIA revelations that China helped Pakistan develop ballistic missile technology will serve only to frighten the west.
China already occupies part of northern Kashmir.
It would be happy for the Tibetan people of Ladakh to fall under its control. It is willing to help Pakistan compete in an expensive and time-consuming large arms race. But China will be less keen to sell small arms that could find their way to its own Muslim insurgents in Xinjiang. With the prospect of mutually assured destruction hanging above south Asia, peace in Kashmir is not a luxury but a necessity. The west must invest in economic and political stability in Pakistan.