After a stop in Japan, Harris is set to arrive in the South Korean capital and visit the heavily fortified Demilitarised Zone (DMZ) between the neighbours on Thursday.

Japan’s coast guard also reported a suspected ballistic missile test.

The launch came two days after South Korea and US forces launched a military drill in waters off the South’s east coast involving an aircraft carrier. On Sunday, North Korea had fired another ballistic missile towards the sea off its east coast.

In a speech hours earlier aboard the destroyer USS Howard destroyer in the Japanese city of Yokosuka, Harris said Sunday’s launch was part of an “illicit weapons program which threatens regional stability and violates multiple UN Security Council resolutions”.

Since 2006, North Korea has been subject to UN sanctions, which the Security Council has steadily and unanimously stepped up over the years to cut off funding for its nuclear weapons and ballistic missile programs.

North Korea rejects the UN resolutions as an infringement of its sovereign right to self-defence and space exploration, and has criticised military exercises by the US and South Korea as proof of their hostile intentions.