Watchdog: nuclear warheads still building up in 4 countries

A Swedish arms watchdog says 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.

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, India, Pakistan, Israel and North Korea together had about 14,935 nuclear weapons, down from 15,395 a year earlier.

The watchdog said Thursday in its 2016 yearbook that the North Korean figures were uncertain.