I dont know much about the war but the fact is that the Communist Parties in India have supported China and due to the coalition governments no government took up serious steps to counter the Chinese interventions in the East of India... And the situation has worsened to such an extent that if China declares a war it will be almost impossible for India to give a strong counter attack...
Thankfully the current government at center is not supported by Communist parties and so the GoI is doing what it has to do "Save our ***" from Chinese intervention by strengthening military base...
As for war I would bet my money on US
more than India and China....After all they are the war makers and war breakers