U.S. officials are increasingly worried about the stability of Pakistan’s government as radical militants – including the Taliban – move within 60 miles of the capital. Why is the situation getting so much worse? How much danger is there of a government collapse? Will the military seize control of the government again if the radicals get closer? What help can the U.S. provide? And are the nukes safe? We ask Daveed Gartenstein-Ross, vice president of research at the Foundation for the Defense of Democracies.