The Chinese aren't using anything as a weapon, that few days worth of "water outage" was a response to the sentiment in India that water can be used as a weapon to destroy and murder a big portion of 220 million people of Pakistan by not giving them water.
In fact, if you look at the above picture, the Chinese can literally dry out the Indus and a few other rivers leaving from the Tibet plateau and can divert 100% of their water to Pakistan's part of Indus, by passing the entire Indian territory. So I guess God always shows us to treat others nicely, because if we harm someone, there may be someone who could harm us the same way?