North Korea said Wednesday its latest ballistic missile tests were personally ordered and monitored by supreme leader Kim Jong-Un and simulated nuclear strikes on US bases in South Korea.

The three missiles launched on Tuesday simulated pre-emptive attacks on South Korean ports and airfields hosting US military "hardware," the North's official KCNA news agency said.

The tests "examined the operational features of the detonating devices of nuclear warheads mounted on the ballistic rockets at the designated altitude over the target area," it said.