Invalid comparison, US-NATO attacking Afghanistan, Iraq, and Vietnam is not the same as US-NATO supplying weapons to India in a war against China. Considering, China will most likely discover weapons transfer via satellite and that will have international repercussions for many western countries. Besides, China is economically vital to the West far more than India. They aren't going to provide Indian military weaponry that will only prolong the war. Besides, even if they gave you weaponry of sophisticated variety your troops still need to learn how to operate the weaponry and master it before it can become effective in the battlefield, Indian army may not have enough time as the next war may very well be a short and decisive one.
Why don't you be specific and tell me what kind of military weaponry do you think US-NATO is going to supply India in a conflict against China?