The interesting twist with the Agni-III is the apparent non-reliance on missile silos. This is a very logical decision. Missile silos can be targeted and taken out with something as simple as GPS-guided conventional munitions, without even resorting to the use of more expensive nuclear weapons. That is not what anyone wants to have happen to their nuclear deterrent force. So, the key to survival is to have a portion of that nuclear deterrence force that will be hard to get. The United States does this with fourteen ballistic-missile nuclear submarines (SSBNs).
However, India does not have the ability to build such platforms yet. But ballistic missiles are the hardest nuclear delivery system to defend against. So, India is going with a mixture of road and rail deployment for the Agni-III. India is learning from the mistakes of some other countries, like Iraq. They dont want fixed sites for valuable assets (and a nations nuclear deterrent is extremely valuable). Instead, they will keep them mobile, and that will make taking them out a much harder task.
This is the next-best thing to having a force of SSBNs or non-nuclear ballistic missile submarines (SSBs), and it is a lot cheaper. With the availability of GPS, targeting is also much simpler, since one can know their position within a matter of meters.
India is pursuing a sea-based component for its nuclear deterrence force, but that will take the longest time to complete (submarines take time to build, and it is doubtful that any nation will license the technology to build a ballistic-missile submarine to India). In the meantime, the road-and-rail-mobile Angi-IIIs, plus the Sukhoi Su-30MKIs fighter-bombers, will form an adequate deterrence force, and India might just decide to keep the mobile Agni-IIIs rather than re-deploy them to missile silos when the sea-based deterrence is completed. Harold C. Hutchison
India will begin flight testing of the Agni-III ballistic missile in the near future. While not quite a true ICBM (it has a range of 4,000 kilometers), it does have enough range to deliver a nuclear warhead anywhere in the Peoples Republic of China or Pakistan. The Agni-III follows the Agni (800-kilometer range) and the Agni-II (2,000-kilometer range), which are currently deployed, primarily against Pakistan.