it's feasible to steal India's monsoon, the question is if China want to get India monsoon or not, I don't invente this idea, same as South North water transfer, the idea from Mao, at that time, we didn't have money and the absolution need to undertake such mega project but now it's become a reality.
Water is the future, when China has the absolute need, we know where and how to get it, you can consider as fantasy dream for now...not rule or international law can prevent China to get the Monsoon in the future.