The North has also repeatedly shunned efforts by the South Korean government to improve relations, repeatedly calling Seoul its most “hostile” adversary.

South Korea’s Joint Chiefs of Staff said on Tuesday they had detected the launches of “several projectiles”, including a short-range ballistic missile, into the Yellow Sea from the North Korean city of Chongju at around 1:00 pm (0400 GMT).

The Yellow Sea is the body of water separating the Korean peninsula from China.

The missiles flew about 80 kilometres (50 miles), Seoul’s military said, adding that it was analysing their specifications and flight range, and had “strengthened surveillance and vigilance in preparation for possible additional launches”.

South Korea, its main security partner the US, and Japan were “maintaining a state of full readiness” and closely sharing intelligence, Seoul’s military said.

The launch was North Korea’s first for 37 days and its eighth this year.

In April, Pyongyang conducted another such test to “verify the characteristics and power of a cluster bomb warhead”, its state media said at the time.

South Korea’s Yonhap news agency reported last week, citing unnamed government sources, that Chinese President Xi Jinping would likely visit North Korea sometime this week.

China is North Korea’s main economic and political backer, though Pyongyang has drawn closer to Russia in recent years.

Neither Beijing nor Pyongyang have yet confirmed Xi’s visit.