This was being mooted since 2003.
@Joe Shearer sir I'm sure you must be knowing about it.
One,US always wanted a neutral territory in Asia from where it can have easy access to middle east and south-eastern countries.
Two, the Indian Navy has proved already that it can fix and fuel US ships. Over time port visits must become a natural event. India is a viable player in supporting all naval missions, including escorting and responding to regional crises. It all began with naval cooperation in the Straits of Malacca during op enduring freedom.
But India has always been adamant that India would consider technology transfer as an important component for a robust military relationship between the two countries. This was the hurdle so far.
US's denial had costed India several delays like in case of LCA project and also after 1998 nuclear sanctions several Sea King naval helicopters were grounded merely because America denied critical components.
Three, we were never too happy with Russian tech. Yes, Russia has been our all weather friend but now that Russia has thawed its relations with Pak and China, it becomes necessary for India to secure its position.
But opening up base in India would also mean that from now Indo - US relation would mature and it will be an "adult to adult" relationship. Indian secret agencies have helped US agencies and tipped them about Taliban, OSL and Al-qaeeda but so far America has always disappointed when it comes to Indian interests.
Obama's recent statement about Pak is a proof to our maturing relationship.
We might soon see Indian officers being sent to America for tech training courses.