I have a huge interest in world poilitics but know the minimal about it. But the topic is so interesting that it can't be left unreplied.

Why should US form an alliance with India? It is already having control over Afganistan and Pakistan (don't feel that Pak is in a position to say "No" to any of the US demands.). So, if it wants to make a base over there, none but India and China would be the first two countries to oppose it. In International Political terms, this can be rephrased as - It will affect the regional balance.

Let me focus some major points related to our context.

1) China and US share very huge mutual economical interests. Its not easy to attack a country with which you have your ties. It is always your people whom you have to answer back home.

2) Now a days, no one dreams of a war between two Nuclear capable countries.

3) In 21st centuary, there are different kind of war that we fight. Take the example of US - USSR war. They call it cold war. No blodshed. Still US defeated USSR. So, even though cold war is over, lot many these kinds of war are going on.

4) Russia - China - India. They are working towards making a common front. I don't know what they call it. But surely, it is as a deterrant against US.

5) Word politics have changed after the emergence of globalization. If you take one decision, it is going to have multi-dimensional effect over everything.

Similarly, there are lot many points. Its Not attack on Taiwan - or attack on China... it's a matter of past... I hope that there are much more intelligent ways to defeat a country instead of chosing an option of military attack.