"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, 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. [...] However, instability in Pakistan has called the extent and durability of these reforms into question. Some observers fear radical takeover of the Pakistani government or diversion of material or technology by personnel within Pakistan's nuclear complex. While U.S. and Pakistani officials continue to express confidence in controls over Pakistan's nuclear weapons, continued instability in the country could impact these safeguards. Furthermore, continued Indian and Pakistani nuclear weapons development could jeopardize strategic stability between the two countries."
CRS Report for Congress, RL34248
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html