As someone in this forum previously said ....."K-4 is a just a stop gap measure ... the real thing would be K-5" .... also India definitely understates it's Ballistic Missile Range's .... A3 has a Range of 3500Km with 2.5 tom warhead ... seriously who's gonna send a 2.5 ton warhead ....
Also the only weapon that will truly give us a really massive second strike capability will be the K4 SLBM, the K4 along with the K15 are going to be deployed with WARHEADS ATTACHED. make no mistake about it that is the reason you deploy an SSBN.
for <500 Km - Prahar
Agni I ----- SRBM
Agni II ---- MRBM
Agni III --- IRBM
Agni V -- ICBM
and Agni IV exclusively for ASAT ...