India’s nuclear expansion not targeted at Pakistan but at China

Chidanand Rajghatta, TNN Jun 16, 2013, 04.57AM IST

Earlier this month, SIPRI, the respected Sweden-based arms control and non-proliferation think tank, reported that China, India, and Pakistan had increased their nuclear arsenals by 10 to 20 weapons each during the past year. In this interview with Chidanand Rajghatta, SIPRI researcher Phillip Schell explains how they estimate the arsenal size of each country and the motivations driving their expansion.
How does one arrive at the number of nuclear weapons that countries have when they don't declare it themselves or confirm your assessment?

http://articles.timesofindia.indiatimes.com/2013-06-16/stoi/40006429_1_nuclear-arsenal-sipri-nuclear-weapons