Nuclear warheads still building up in 4 countries: watchdog

COPENHAGEN -- The global number of nuclear warheads dropped last year, but it seems China, India, North Korea and Pakistan are expanding the size of their atomic arsenals, a Swedish arms watchdog said Thursday. The Stockholm International Peace Research Institute says developments in North Korea's nuclear program "contributed to international political instability with potentially serious knock-on effects." SIPRI says that as of January 2017 the United States, Russia, Britain, France, China, Ind