While nobody (at least in the US) knows for sure how many nuclear weapons India and Pakistan has, conventional wisdom has given Indian an arsenal of about 50 and Pakistan struggling to push its stockpile beyond 20. But new information by a US intelligence agency puts the Pakistani total at no less than 25 and perhaps 50, while India's arsenal is between 20 and 30. What causes these discrepancies? It's all a guess put together from various bits of information. One data point is to estimate how many they could have built with the available industry. Another is to count storage facilities. Another theory is that Pakistan may be building smaller "tactical" weapons while India originally built larger strategic weapons and is now scrambling to design and build smaller tactical weapons. In the end, it does not matter much. Neither country has enough weapons to effectively destroy the other, making "mutual assured destruction" (which prevented a US-USSR war) something far less stable, perhaps "mutually assured major damage".--Stephen V Cole