What would a missile defense system for India achieve?

Manasi alerts me to this Bulletin of the Atomic Scientists article on a possible Indian missile defense system developed with help from the US. As always, the questions to be asked are; Would it work? and What would it achieve?

I have often talked about the recurring problems with conceived US global missile defense systems as pointed out by various experts over the years and the fact that missile defense in one form or the other has been an unrealized dream for US presidents for 40 years. In India missile defense acquires a very different character from the proposed US missile defense systems against supposed ICBMs from Iran or North Korea. Pakistan is a stone's throw away from the Indian border, and as Gopalaswamy in this essay and Mian and others in a more detailed 2003 Science and Global Security article explain, flight time for a missile to reach New Delhi from Pakistan would be about 4-7 mins. What would the Indian authorities do in such a short time? Detecting any such signal and confirming it as a true one would consume all the time needed for authorities to determine it as a hostile missile launch from Pakistan. The detection would be done by the Arrow system that India acquired from Israel that's located about 200 kms from Delhi. But because of this very short flight time, there would be no time for further deliberation and any response would have to be a predetermined one.

As Mian and his colleagues state in their article, there are two forms which predetermined response could take; civil defense and/or retaliation. Retaliation if at all possible in such a short time would have to be very quick. Retaliation against nuclear-tipped missiles would be very difficult in the boost phase (right after the missile lifts off, which gives the defense about 90 seconds to destroy the missile) and extremely dangerous in the terminal phase (the phase before the missile hits the target during which its destruction could nonetheless cause great damage to the home territory). As both articles state, with such predetermined responses the threat of false alarms and nuclear conflict increases, an assertion borne out by several close calls during the Cold War even when the response time was much longer.

As the articles state, the prospect of talks on missile defense between the US and India is definitely a welcome sign of relations between the two countries, but we should think twice before spending taxpayers' money and scientific and human capital on a system that may not really work, but which may encourage the adversary to build more offensive weapons; after all a single one getting through would be enough to cause havoc. As Gopalaswamy says, ultimately technology will decide the operational capability of such a system. Perhaps more attention should be paid to civil defense, a gesture both prudent and practical, and perhaps less threatening.

Reference:
Mian, Z., Rajaraman, R., Ramana, M.V., "Early Warning in South Asia-Constraints and Implications". Science and Global Security, 11: 109-150, 2003