We estimate that Pakistan now has a nuclear weapons stockpile of approximately 170 warheads (See Table 1). The US Defense Intelligence Agency projected in 1999 that Pakistan would have 60 to 80 warheads by 2020 (US Defense Intelligence Agency 1999, 38), but several new weapon systems have been fielded and developed since then, which leads us to a higher estimate. Our estimate comes with considerable uncertainty because neither Pakistan nor other countries publish much information about the Pakistani nuclear arsenal.