The vehement denials are in. But the waters are already muddied, especially given contextual developments. Both America and Bangladesh's pooh-pooing of an Indian news report that the United States (US) Pacific Command (PACOM) was looking to park the Seventh Fleet at Chittagong sometime in the future, doesn't really mean that such a move would be completely out of the ordinary. Nor would it be an aspect of Obama's pivot to Asia that India will find acceptable.
When I first read the news report talking about an American Naval interest in Chittagong, my thoughts went to the following graphic (see image 1.1 below) I had seen in 2010 in the Washington-based Center For Strategic and Budgetary Assessment, the CSBA's September 2010 report, "Sustaining America's Advantage in Long Range Strike" (SALS).
The image depicts the flight path that the proposed Next Generation Bomber (NGB), being sought by the US Air Force, might take to strike targets deep within China. It is important to note that CSBA is the leading think-tank analyzing the need for the Pentagon's new AirSea Battle (ASB) concept, which looks to develop joint naval and air force doctrines and systems that would allow the US to defeat so-called Anti-Access/ Area Denial (A2/AD) weapons, and thereby continue to hold targets deep within any hostile nation's territory at risk. It was CSBA which came out with the report "AirSea Battle", a few months prior to SALS and believes that the NGB is a key enabler of any successful ASB strategy.
Source: Sustaining America's Advantage in Long Range Strike, CSBA
As we can see above, one of the possible routes the NGB or even the existing B-2 of today can take to Delingha in China (a leading light in the development of new A2/AD systems), according to the CSBA release, traverses the Bay Of Bengal, over Sri Lanka, Bangladesh, and indeed North-eastern India as well. The choice of target itself is interesting, but let us leave that aside for now. That a possible journey for a proposed new American stealth bomber actually begins from Diego Garcia in the Indian Ocean and includes flying over the territory of three Sovereign nations, is a noteworthy feature in light of Obama's pivot to Asia and the concomitant unveiling of ASB.
Now the reasons for taking such a route are, of course, sound enough. China's integrated air defense system (IADS) isn't particularly dense in the region and although new air bases have been built in south-western China, the threat metric to an ingressing NGB is weaker than what it would face on China's eastern seaboard in the South China Sea.
Of course, the NGB, given that it will have less persistence than the B-2, will require at least one refueling on a mission of this sort that begins from Diego Garcia. And it is here that the next graphic (see image 1.2 below) from the same report i.e. SALS depicts an even more interesting picture.
Source: Sustaining America's Advantage in Long Range Strike, CSBA
What we see above is a possible refueling action for the NGB that takes place, just off the Bangladeshi coast, en-route to Delingha, not too far from where Chittagong is. Now even though China has a relatively weaker air defence net oriented in this direction, such a refueling is better off taking place in sanitized air space, and that means some sort of air cover is envisioned for the NGB and the tanker, as they meet off the coast of Bangladesh.
What better way to provide that air cover than have the Seventh Fleet with its Carrier Battle Group stationed at Chittagong?
Moreover most of China's A2/AD systems (like its best air defences) are also oriented towards the South China Sea. And the most touted A2/AD system of all - China's new DF-21D anti-ship ballistic missile relies on a network of land based sensors ( in addition to space based ones) to actually accomplish its role of putting at risk large moving surface craft such as Aircraft Carriers at sea. Unlike the eastern Chinese seaboard, Beijing does not have anything like the over the horizon (OTH) targeting radars and other sensors oriented towards the Bay of Bengal at moment that will make something like the DF-21D to viably project power. It may have some suspected SIGINT facilities on Myanmarese soil, but given Myanmar's rapprochement with the West anything more substantial is looking increasingly unlikely. Indeed Myanmar's re-entry into the broader comity of nations will mean that Beijing's military plans for the Myanmarese coastline are now looking rather dicey.
So, the Seventh Fleet operating in the Northern Indian Ocean is actually an excellent prospect for a Pentagon looking to roll out an effective ASB posture. It will certainly enable the kind of US Navy-Air force cooperation that ASB wants to jointly defeat A2/AD networks in an inside out fashion. In fact future American stealth UCAVS can also traverse a similar route not to mention land attack cruise missiles fired by both surface and sub-surface constituents of the Seventh Fleet.
Now, CSBA is an independent and non-profit think-tank and what we see in this piece isn't of course Official US government thinking. However, CSBA does seem to have emerged as a think tank with a very important ASB practice if we could call it that, and the NGB flight path depictions discussed above either assume that India (and indeed Bangladesh) are in a deep alliance with the US, such that they make their airspace available for such operations or that the NGB will be so stealthy that it will penetrate Indian airspace at will before doing the same to the Chinese. Neither is, of course, a particularly settling prospect to India. Not to mention that a Seventh Fleet in the Bay of Bengal impinges on a core area of interest for India and can surveillance seed numerous Indian facilities in the vicinity, including missile test ranges.
I am sure this is not the kind of partnership India is interested in with the US.
Why does America want a base in Bangladesh? (And why India isn't amused)
Apparently Deingha(Delhi, Qinghai) is a major missile centre for China.
and that's not going to happen. 
