"Pakistan's nuclear arsenal probably consists of approximately 90-110 nuclear warheads, although it could be larger. Islamabad is producing fissile material, adding to related production facilities, and deploying additional delivery vehicles. These steps could enable Pakistan to undertake both quantitative and qualitative improvements to its nuclear arsenal. Whether and to what extent Pakistan's current expansion of its nuclear weapons-related facilities is a response to the 2008 U.S.-India nuclear cooperation agreement is unclear. Islamabad does not have a public, detailed nuclear doctrine, but its 'minimum credible deterrent' is widely regarded as designed to dissuade India from taking military action against Pakistan."
CRS Report for Congress, RL34248
United States. Department of State, Foreign Press Centers, Bureau of Public Affairs: http://www.fpc.state.gov/