In early April North Korea declared that it was cancelling the armistice which ended the 1950s Korean war and was “in a state of war” with South Korea. It threatened to hit the USA with nuclear weapons.
It has withdrawn 50,000 North Korean workers from a special industrial zone which is on the northern side of the Korean border but houses South Korean companies.
No-one knows what North Korea may do further. The 86-year-old Fidel Castro has called the situation “incredible and absurd”, and urged North Korea to restraint, while also denouncing any US military action.