North Korea's Nuclear Path

Ever since signing the nuclear Non-Proliferation Treaty and agreeing to U.N. safeguards two decades ago, North Korea has resisted inspections of its nuclear facilities. In 2003, it withdrew from the NPT and expelled U.N. nuclear inspectors. A tense standoff followed, and on Thursday North Korea announced it had produced nuclear weapons as a deterrent against the United States.

SOURCES: Nuclear Threat Initiative, Arms Control Association, Monterey Institute of International Studies, Federation of American Scientists, news services | The Washington Post