North Korea launched around a dozen short-range ballistic missiles eastwards from an area near Pyongyang on August 20, South Korea’s military said, according to Kyodo News.

Japan’s Defence Ministry said multiple missiles travelled about 320 km and reached a maximum altitude of about 90 km.

Defence Minister Shinjiro Koizumi, who was visiting New Delhi, said Tokyo had lodged a strong protest with Pyongyang.

The missiles are believed to have fallen outside Japan’s exclusive economic zone, while Japanese authorities were working with the US and South Korea to analyse the launches, according to Kyodo News.

The launches came during a large-scale military exercise by the US and South Korea. The exercise is being conducted through August 22 to prepare for a contingency on the Korean peninsula.

The exercise had originally been scheduled to run through August 27. It was shortened at the direction of US President Donald Trump.

Kim Yo Jong, the influential younger sister of North Korean leader Kim Jong Un, said in a statement carried by North Korean state media that reducing the scale of the exercise did not change its hostile nature.

The latest launches have added to tensions on the Korean peninsula while the US and South Korea conduct their joint military drills.

In Tokyo, Prime Minister Sanae Takaichi instructed relevant government agencies to make every effort to gather and analyse information. She also directed officials to provide the public with accurate updates and ensure the safety of aircraft and vessels.

Japan is monitoring the launches in co-ordination with its allies. The Defence Ministry said the missiles travelled approximately 320 km and reached a maximum altitude of about 90 km.

The launches were North Korea’s third ballistic missile launch this month. The previous launches took place on August 6 and August 12.

The latest activity comes as Pyongyang continues to object to joint US-South Korean military exercises, which it regards as hostile. The US and South Korea have maintained the drills as part of preparations for a potential contingency on the Korean peninsula.