North Korea's state-run television aired a video footage of the country's test of a new "railway-borne missile system" on Thursday.
The missiles launched on Wednesday flew 800 km (497 miles) before striking a target in the sea off North Korea's east coast, the state media said.
The video showed an olive-green missile rising on a column of smoke and flame from the roof of a train parked on tracks in a mountainous area.
South Korean and Japanese authorities said they had detected the launch of two ballistic missiles from North Korea, just days after it tested a cruise missile that analysts said could have nuclear capabilities.
The North Korean launches came the same day that South Korea tested a submarine-launched ballistic missile (SLBM), becoming the first country without nuclear weapons to develop such a system.