Circular Error Probable

The accuracy of a ballistic missile is expressed in terms of its Circular Error Probable (CEP). This measures the radius of a circle within which 50% of the missiles fired will impact. Thus if the Agni IRBM has a CEP of 100 metres, then 50% of missiles fired at a given target should impact within 100 metres of their intended target and the remaining 50% will impact more than 100 metres from their target. Therefore, an Agni fitted with a conventional high-explosive warhead and a CEP of 100 metres would normally be expected to destroy or disable fixed military targets such as a Command & Control facility.

If the Agni was being used only for the purpose of a nuclear strike, then even if it had a CEP of 1 km, it would be effective against a soft and undefended area target, such as a city. The damage caused by a nuclear explosion 1 km away will still be sufficient to destroy all but the most hardened of installations, whereas that caused by a conventional high explosive will not. Similarly, if the Agni is armed with chemical and biological weapons (CBW) or radiological weapons it is likely to cause significant damage to fixed military and soft targets even if it has a large CEP.