Radiation levels inside a damaged reactor at Japan’s Fukushima nuclear plant have hit a record high, and are the worst since the plant suffered a triple meltdown nearly six years ago. The latest readings now pose a serious challenge as officials prepare to dismantle the stricken facility. Radiation levels inside the containment vessel of reactor No. 2 at Fukushima has reached 530 sieverts per hour—a figure described by experts as “unimaginable.” The readings, taken by Tokyo Electric Power Co. Holdings Inc...

The nuclear icebreaker Lenin, the pride and joy of the Soviet Union's Arctic great game, lies at perpetual anchor in the frigid water here. A relic of the Cold War, it is now a museum.

Atomic scientists reset their symbolic "Doomsday Clock" to its closest time to midnight in 64 years on Thursday, saying the world was closer to catastrophe due to threats such as nuclear weapons, climate change and Donald Trump's election as U.S. president.

China and Russia have agreed to take further unspecified "countermeasures" in response to a U.S. plan to deploy an anti-missile system in South Korea, state news agency Xinhua reported on Friday.

The Cold War saw numerous submarine accidents, especially on the Soviet side. For much of its existence, the USSR tried to maintain a world-beating military with a second-rate economy. Throughout the era, the Soviets struggled to maintain their magnificent weapons of war. In the effort to close this gap, the crews of Soviet submarines often paid with their lives. But only one submarine had the poor luck to sink twice.

South Korea has elite troops on standby ready to assassinate Kim Jong Un if the country feels threatened by North Korean nuclear weapons, the country's defense minister revealed this week. Asked in parliament Wednesday if there was a special forces unit already assembled that could eliminate North Korean leader, Kim Jong Un, Han Min-koo said: "Yes, we do have such a plan. "

For decades, they were relatively common.

North Korea is celebrating the launch of a ballistic missile from a submarine. Regime leader Kim Jong Un says his nuclear weapons can now strike the US mainland. Should Americans be worried?

A picture in the state-run Rodong Sinmum newspaper shows the leader watching a missile test alongside his generals. The map in front of him charts the trajectories of three missiles tested by North Korea in a practice nuclear strike this week. But it might also reveal the first target he wants to annihilate with his nukes – and it's a city that's home to several million people.

North Korea may be significantly expanding its nuclear weapons production and could have added six or more weapons to its stockpile in the last 18 months, a U.S. research institute said on Tuesday. The Washington-based Institute for Science and International Security (ISIS) estimated last year that North Korea had 10 to 16 nuclear weapons at the end of 2014. It based that conclusion on an analysis of the country's production of weapons-grade uranium and plutonium recovered from spent nuclear fuel.

As it seeks to modernize its nuclear arsenal, the United States faces a big choice, one which Barack Obama failed to mention during his moving Hiroshima speech on May 27.The Conversation Should we spend a trillion dollars to replace each of our thousands of nuclear warheads with a more sophisticated substitute attached to a more lethal delivery system? Or should we keep only enough nuclear weapons needed for a devastatingly effective deterrence against any nuclear aggressor, investing the money saved into other means of making our nation more secure?

The visit has been debated within the White House, with President Obama reluctant to be seen as apologizing to Japan. “He will not revisit the decision to use the atomic bomb at the end of World War II,” an aide said.

It will be 30 years ago Tuesday that Pripyat and the nearby Chernobyl nuclear plant became synonymous with nuclear disaster, that the word Chernobyl came to mean more than just a little village in rural Ukraine.

Activities at North Korea's Punggye-ri nuclear site are showing Pyongyang is getting ready for its fifth nuclear test, which could happen as early as Saturday. U.S. and South Korea military surveillance captured the movements showing all preparations are complete, local television network SBS reported. Satellite imagery showed a significant number of vehicles along with other equipment were no longer visible on site.

A solid-fuel rocket engine North Korea tested in March was built with technology from Iran, an Israeli analyst said. Tal Inbar, of Israel's Fisher Institute for Air and Space Strategic Studies, said Pyongyang has also made significant progress in developing ballistic missile technology, Voice of America reported Tuesday. Inbar made the statements at a congressional briefing addressing the "ballistic axis," a reference to Iran's and North Korea's space program.

Georgia's security service said on Monday it had detained six Georgian and Armenian citizens who were trying to sell $200 million worth of uranium-238. Georgia's security service did not say whether the group had a buyer for the uranium. Nor did it say where the group had acquired it. However, Georgia is a former member of the Soviet Union, and world leaders have been concerned about the security of Soviet nuclear weapons since it broke up in 1991.

At first glance, it’s hard to know what’s happening in this picture. A giant mushroom seems to have sprouted in a factory floor, where ghostly men in hardhats seem to be working. But there’s something undeniably eerie about the scene, for good reason. You’re looking at the largest agglomeration of one of the most toxic substances ever created: corium.

North Korea said Saturday it had successfully tested an engine designed for an inter-continental ballistic missile (ICBM) that would "guarantee" an eventual nuclear strike on the US mainland. It was the latest in a series of claims by Pyongyang of significant breakthroughs in both its nuclear

Satellite images suggest "significant activity" is taking place at a North Korean laboratory that could separate plutonium for nuclear weapons. The photos appear on 38 North, a US website that monitors sensitive sites in the country. The website says that during the past five weeks exhaust plumes have been seen two or three times at the radiochemical laboratory complex at Yongbyon.

Japanese regulators on Wednesday approved the use of a giant refrigeration system to create an unprecedented underground frozen barrier around buildings at the wrecked Fukushima nuclear plant in an attempt to contain leaking radioactive water. The Nuclear Regulation Authority said the...