Seoul: North Korea fired suspected short-range ballistic missiles off its east coast on Friday, South Korea’s military said, a day after South Korea and the US flew powerful fighter jets in a joint drill that the North views as a major security threat.

South Korea's Joint Chiefs of Staff said the weapons launched from the North's east coast Wonsan region travelled about 300 kilometres (185 miles) before landing in the waters between the Korean Peninsula and Japan. Japan’s Chief Cabinet Secretary Yoshimasa Hayashi said a North Korean missile landed outside Japan's exclusive economic zone.

South Korea's Joint Chiefs of Staff statement called the launches “a clear provocation” that threatens peace on the Korean Peninsula. It said South Korea will maintain a firm readiness to repel potential aggressions by North Korea in conjunction with the military alliance with the United States.

North Korea has extended its run of weapons testing in recent months as part of its efforts to enlarge and modernise its arsenal while diplomacy with the United States and South Korea remains stalled.

Last week, North Korean leader Kim Jong Un supervised the test firing of a new multiple rocket launch system, according to the North’s state media.

North Korea says it has been forced to boost its nuclear and missile programmes to deal with US-led hostilities. North Korea cites expanded US-South Korean military training, which it calls an invasion rehearsal.

Many foreign experts say North Korea uses its rivals' military drills as a pretext for building a larger weapons arsenal in the belief that it would boost its leverage in future diplomacy with the US.

On Thursday, two South Korean F-35As and two US F-22 Raptors were mobilised for a combined aerial exercise over the central region of South Korea. North Korea is extremely sensitive to the deployment of sophisticated US aircraft. It was reportedly the first deployment of a U.S. F-22 to South Korea in seven months.

The North's official Korean Central News Agency said Friday the re-deployment of the US F-22s for joint training with South Korea is “another clear proof of the hostile nature of the US” which seeks “a showdown of force” with North Korea.

KCNA accuses “the military gangsters” of South Korea of intensifying tensions to keep pace with “their master's confrontation scheme” against the North.

It warned the F-22 flyovers “will only precipitate the advent of a situation that the US does not want to see." But it didn't elaborate on what steps North Korea would take.

Also Friday, Kim's sister and senior official Kim Yo Jong said North Korea’s recent weapons tests were part of the country’s five-year arms buildup plan launched in 2021.

She said the recently tested weapons are designed to attack Seoul, the South Korean capital, and denied outside speculation that the tests were meant to display weapons that North Korea plans to export to Russia.

“We don’t conceal the fact that such weapons will be used to prevent Seoul from inventing any idle thinking,” Kim Yo Jong said in a statement carried by KCNA.