The very real prospect of India and Pakistan starting the first two sided nuclear war has generated a lot of speculation on exactly what would happen. Calculating the destruction and loss of life if weapons are used is relatively easy. Much more difficult, and important, is figuring out how many of the weapons will actually work. All bombs have mechanisms (arming devices) in them to prevent accidental detonation. This sort of thing is particularly important for nuclear weapons, and the Indian and Pakistani weapons designers know it. But knowledge does not immediately translate into practice, and we know from the American and Russian experience that arming devices on a nuclear weapon (often as many as five different ones) can easily fail (from design, manufacturing or installation flaws.) It takes a lot of practical experience to develop arming devices that work every time. The Indians and Pakistanis are known for sloppy military engineering. Just take a look at their safety and reliability records for military equipment (especially aircraft and ships.) The most common guess for the size of each nations current nuclear arsenal is 20 weapons for Pakistan and up to a hundred for India. What percentage will fail? Perhaps up to fifty percent. If they fought their nuclear war 5-10 years from now, the failure rate would be a lot less. But there is yet another problem; reliability of delivery systems. While both sides have ballistic missiles that could carry a nuclear warhead, producing weapons small enough, and reliable enough, to be used in a ballistic missile is yet another daunting engineering task. A nuclear war in 2002 would probably see both nations using aircraft to deliver the weapons. Aircraft can be intercepted, and both nations will probably make exceptional efforts to intercept enemy bombers making for their major cities. If both sides make a major effort, some nukes will hit some cities and detonate. But it's unlikely that all the weapons in each nation's nuclear arsenal will detonate, and that's one case where we can be grateful for inadequate engineering.