Underground nuclear weapons testing

South Korea, the United States and Japan kicked off major new military exercises on Thursday, Seoul's Joint Chiefs of Staff said, as the allies seek to counter growing threats from Pyongyang.

The drills, dubbed "Freedom Edge", will focus on ballistic missile and air defences, anti-submarine warfare and defensive cyber training, among other areas, the JCS said in a statement.

North Korea has tested a "super-large warhead" designed for a strategic cruise missile, state media said Saturday, the most recent test since U.N. sanctions monitoring against the nuclear-armed nation was upended last month by Russia.

In a move that has raised alarms across the international community, North Korea launched several cruise missiles from its west coast towards the Yellow Sea on Wednesday morning. The Joint Chiefs of Staff in South Korea reported the missile launch, emphasizing that the details are under close analysis by intelligence authorities in both South Korea and the United States.

North Korea has announced the successful testing of its "underwater nuclear weapons system," specifically a nuclear-armed underwater drone known as the Haeil-5-23 system, as reported by the BBC. While North Korea has previously mentioned tests of this system, the weapon's existence has not been independently verified.

North Korean leader Kim Jong Un said his country has built its first-ever military spy satellite and that he planned to launch it on an undisclosed date, state media reported Wednesday.

North Korea said Friday it flight-tested a solid-fuel intercontinental ballistic missile for the first time, a possible breakthrough in its efforts to acquire a more powerful, harder-to-detect weapon targeting the continental United States.

According to state television, he also said that Pyongyang should be fully prepared to use nuclear weapons at any time.
Kim made the remarks during an inspection of the country's nuclear weapons program, during which the trigger technology was tested.

North Korean leader Kim Jong-un has urged his country to be ready to launch nuclear strikes at any moment, accusing the US and South Korea of expanding joint military exercises involving US nuclear-capable weapons, BTA and Reuters reported, citing local media: state agency KCNA.

North Korean leader Kim Jong Un led two days of military drills "simulating a nuclear counterattack", including the launch of a ballistic missile, state media reported Monday.

The United States, Japan and South Korea warned Wednesday that a North Korean nuclear test would warrant an "unprecedentedly strong response", vowing unity after a blitz of missile launches from the hermit state.

Following talks in Tokyo, the three nations' deputy foreign ministers said they would ramp up their deterrence in the region.