Pakistan's nuclear weapon program dates back to at least 1974 and is very advanced, although not as advanced as larger and richer India's is. Since 1987 Pakistan's nuclear weapons have been miniaturized to allow delivery by Pakistan's Air Force fighters and by its IRBMs (intermediate range ballistic missiles) and cruise missiles (including ground/air/naval surface/submarine launched versions).
Pakistan uses both highly enriched uranium and plutonium for its nuclear weapons. The Khushab nuclear site has sufficient plutonium production for 40 to 50 warheads a year by itself. This site is coming on line and is a major expansion of Pakistani plutonium reprocessing capabilities; a fact that concerns a number of nations including America, India, and Israel. In 2000, US military intelligence reportedly estimated Pakistani nuclear weapons at approximately 100 in number. A number of 200 in late 2008/early 2009 is very probable.