Heightened radioactivity levels were found outside a nuclear waste tank in the US state of Washington, officials said Friday, in a new alert about a site used to make Cold War-era bombs.
Iran's newly-elected president Hassan Rowhani ruled out any halt to the nuclear activity that has drawn UN sanctions but said he hoped an early deal could be reached to allay the concerns of major powers.
South Korea on Monday joined the United States in insisting that rival North Korea take "concrete" steps towards abandoning its nuclear weapons if it genuinely wants to end its international isolation.
North Korea on Saturday made a fresh vow to build up its nuclear deterrent in the face of "threats of war" from the United States and a "policy of confrontation" from the South.
Iran is working round the clock to enlarge its nuclear infrastructure with the eventual aim of developing an industry capable of building up to 30 bombs a year.
North Korea may be just one or two months away from restarting a reactor to produce plutonium, potentially allowing the regime to ramp up its nuclear weapons program.
Just weeks after a visit to regional rival China, French President Francois Hollande arrives in Japan on Thursday, hoping to close deals on nuclear cooperation and in the aviation sector.
South Korea and the United States began extended negotiations Monday on renewing their civilian nuclear pact, with Seoul pushing for the right to produce its own nuclear fuel.
Iran's defiant expansion of its nuclear programme and 10 failed meetings with the IAEA will dominate a gathering of the UN body's board starting Monday.
An important recent development in Iran's nuclear programme, if it continues, might help to ease international fears that Tehran wants the bomb, but serious questions still remain.
North Korea vowed Wednesday to tighten its hold on its "priceless" nuclear deterrent, confounding reports that it might be willing to resume multilateral talks on denuclearisation.
South Korea on Monday brushed off an apparent offer by North Korea to resume nuclear disarmament talks, and chided Pyongyang for a recent personal attack on its president Park Geun-Hye.
Japan's nuclear watchdog said Wednesday that one reactor was sitting directly above an active tectonic fault, effectively ruling out a restart forever.
Nuclear talks between Iran and the UN atomic agency failed yet again Wednesday, as the top US diplomat in separate six-party negotiations warned Washington's patience was wearing thin.