Why do I say inevitable? India needs water, and it is damming rivers to get it. Those rivers flow into Pakistan, which also needs water. Soon there will not be enough to go around. Both countries are nuclear.
I agree with the first part of your post, but disagree with the second part.
India mostly depends upon River Ganges and River Brahmaputra for water. R. Ganges originate within India, while R. Brahmaputra originates in Tibet. China is currently considering to construct a major dam in Brahmaputra, which will divert most of its water.
On the other hand, Pakistan depends upon R. Indus for most of its water needs. Some 75% of its waters originate within Pakistan, some 15% in Tibet and the remaining in India.