"Pakistan's nuclear arsenal probably consists of approximately 110-130 nuclear warheads, although it could have more. Islamabad is producing fissile material, adding to related production facilities, and deploying additional nuclear weapons and new types of delivery vehicles. Pakistan's nuclear arsenal is widely regarded as designed to dissuade India from taking military action against Pakistan, but Islamabad's expansion of its nuclear arsenal, development of new types of nuclear weapons, and adoption of a doctrine called 'full spectrum deterrence' have led some observers to express concern about an increased risk of nuclear conflict between Pakistan and India, which also continues to expand its nuclear arsenal. Pakistan has in recent years taken a number of steps to increase international confidence in the security of its nuclear arsenal. Moreover, Pakistani and U.S. officials argue that, since the 2004 revelations about a procurement network run by former Pakistani nuclear official A. Q. Khan, Islamabad has taken a number of steps to improve its nuclear security and to prevent further proliferation of nuclear-related technologies and materials. A number of important initiatives, such as strengthened export control laws, improved personnel security, and international nuclear security cooperation programs, have improved Pakistan's nuclear security."
CRS Report for Congress, RL34248
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html