As part of the top-secret Manhattan Project, government scientists and the U.S. military dropped the first atomic bomb in the New Mexico desert in 1945.
North Korea suggested it might call off its 20-month suspension of nuclear and missile tests because of summertime U.S.-South Korean military drills that the North calls preparation for an eventual invasion.
Iran warned European partners in its faltering nuclear deal on Wednesday that Tehran will increase its enrichment of uranium to "any amount that we want."
Iran said Monday that its stockpile of enriched uranium will surpass limits set by the 2015 international nuclear deal 10 days from now.
North Korea fired two suspected short-range missiles on Thursday. The launch was a possible warning that missile talks with Washington could be in danger.
India and Pakistan: Scholars disagree about whether nuclear weapons stabilize or destabilize relations between adversaries.
Russian President Vladimir Putin said that his country's new missiles would point toward the United States if Washington deploys missiles in Europe.
This may be the first time in history that a major military power has elected not to invest in extensive defenses against the biggest threat to its survival.
Activists asked a judge to make documents public from a 27-year-old criminal investigation into a former nuclear weapons plant with a history of fires, leaks and spills.