According to non-conventional arms expert of the Quaid-i-Azam University in Islamabad Mansoor Ahmed, those reports can be the Pakistan government's reaction on developing Indian strategic nuclear program. Particularly, in Jan 2012 Russian shipyard Zvezda leased Project 971U nuclear-powered attack submarine K-152 Nerpa to Indian Navy.
Besides, India is engaged in designing and construction of own Arihant-class nuclear-powered submarines. In total, it is planned to build five subs of this type based on Soviet Project 670 Skat. The first Arihant-class submarine is expected to join Indian Navy by the end of 2012.
So far, it is still unclear whether Pakistan possesses technologies to create relatively compact and reliable submarine-based nuclear reactor. It is unknown what kind of nuclear submarines Pakistan wants to acquire, either attack ones or armed with ballistic missiles.