What is driving strategic convergence between Washington and Delhi is Beijing. But the United states and India don’t need a treaty alliance. It is not about deferring to Indian sensibilities that may cling to the country’s nonalignment legacy, or crave strategic autonomy, or envision India as independent balancer in South Asia. No. There just isn’t a need for a defensive alliance to deal with China.
No one is trying to deter or contain China. What is required is a regional structure to manage China’s disruptive influence in the region. Beijing is now attempting to rewrite international norms: threatening freedom of the commons, intimidating smaller regional powers and spreading corrupt practices. What Washington and Delhi have in common is not the desire to counter China per se, but a desire to foster peace and prosperity in the Indo-Pacific—and to deal with Beijing when it undermines that effort.
Further, India has issues in the region which are largely its own concern. They don’t want or need an American security commitment to address them. Indeed, embroiling the Americans in issues like Kashmir makes things worse, not better.
http://nationalinterest.org/feature/strong-us-india-partnership-our-strategic-interest-23624