The North's Missile General Bureau said the test-fire is a "process of constant updating of the weapon system and a regular and obligatory activity of the agency and its affiliated defence science institutes," according to the Korean Central News Agency (KCNA) as quoted by Yonhap news agency.

It is still not clear how far the missile flew.

The South Korean military told Yohap News Agency that the North's latest launch appears to be aimed at upgrading the capability of the existing cruise missiles, but did not provide further details.

"The flight distance of North Korea's cruise missiles fired the previous day was shorter compared with previous launches," Col. Lee Sung-jun, spokesperson of the Joint Chiefs of Staff, said in a regular press briefing as quoted by the news agency.

"We detected and tracked the cruise missile launched by North Korea in real-time. It disappeared at the final stage, and further analysis is needed to determine the circumstances surrounding that," he said.