This article lays out India's growing ambitions to project power west and east to make India a dominant naval power in the Indian Ocean:
Recent developments in the Indian Ocean have been a witness to India’s mustering enough political will to advance its regional interests through actionable deliverables, visibly in opposition to mere notional assertions of the past. As India reorients its Indian Ocean policy, a tripartite transformation is underway—a regional outlook that ties together India’s Act East policy, its Look West policy and, most noteworthy, its cooperation with the United States in the regional maritime domain.
This is true. And I think it will probably be good enough to prevent the Chinese navy from having anything but a short but exciting life in the Indian Ocean even if America does not join the fray.
But China will have a potent weapon to attack the Indian navy in the Indian Ocean without even running the gauntlet through waters filled with Indian allies to breach the Andaman Islands barrier--the anti-ship ballistic missile:
Given the difficulty of projecting conventional Chinese naval power into the Bay of Bengal and points west, couldn't the Chinese use their string of pearls to target India's much smaller (than ours) navy with ship-killing ballistic missiles? The DF-21 would only be of limited value, but if the capability was expanded up the chain of missiles a bit more, the reach of China's anti-ship capabilities would extend to the Persian Gulf[.]
Note the map I displayed in that post:
The DF-21 doesn't have the range--if based in China--to be a major threat. But if the technology is developed and used for longer range missiles, China gains the ability to target India's navy without ever entering the Indian Ocean.
If India wants to act in any compass direction, India needs to look up and act high with defenses that protect their capital ships from a bolt from the blue.
UPDATE: For that matter, if the Chinese can put this type of capability on ICBMs, we'll have to take care not to pull this type of basing even in our home waters.
And don't forget that an enemy can get close when we are technically at peace until they pull the trigger.
UPDATE: Ah, Strategypage has a timely post:
In May 2016 India conducted another test of its ABM (anti-ballistic missile), successfully launching one of the smaller of the two interceptor missile models the AAD (Advanced Air Defense) system uses. That was the twelfth AAD test, of which 75 percent have been a success. The other AAD missile is the Prithvi Air Defense (PAD) missile. This is the larger of the two and is used for high altitude (50-80 kilometers up) interception. The short range AAD missile is used for low altitude (up to 30 kilometers) intercepts. The two missiles, in conjunction with a radar system based on the Israeli Green Pine (used with the Arrow anti-missile missile) provide defense from ballistic missiles fired as far as 5,000 kilometers away.
Although this is discussed in relation to defending Indian cities against nuclear weapons, anti-ship ballistic missiles would be a more likely threat.