LOL, you do know that the USA's closest partner in the region has always been Pakistan, right?
In the 1970's war, America even sent a carrier group to intimidate India, and to show support to Pakistan.
And today, due to the WoT, the USA-Pakistan alliance has become even more important for America.
Regarding the USA and China, this is what Obama said:
BBC NEWS | Business | US-China ties 'to shape century'
The USA and China have the two largest economies on Earth (India is not even in the top ten largest economies) and share the largest bilateral economic relationship in the world. China+Pakistan combined are strategically/economically vital for America, unlike India. India has always aligned itself with Russia.