North Korea launches ballistic missiles prompting 'stern protest'

Japan and South Korea have criticised missile tests launched by North Korea.

Japan has lodged a "stern protest" over the tests according to local media.

North Korea has fired two short-range ballistic missiles into the sea off its eastern coast, with one flying more than 600 kilometres, according to South Korea's military.

The launches came days after Pyongyang reasserted its status as a nuclear-armed state and rejected a United Nations's resolution demanding it halt its nuclear activities.

South Korea's military said the first missile was launched about 3:00pm Sunday local time from the Wonsan area and flew about 450 kilometres into the East Sea, a body of water also called the Sea of Japan.

"Our military detected an additional short-range ballistic missile launched from the Wonsan area of North Korea towards the East Sea at around 5:50pm," South Korea's Joint Chiefs of Staff (JCS) said.

The second missile "flew more than 600 kilometres, and South Korean and US authorities are conducting a detailed analysis to determine its exact specifications," it said.

The JCS said South Korea, the United States and Japan had been "tracking and sharing relevant developments from the initial stage of the launch".

Japan lodged a "stern protest" with North Korea over the launches, condemning them as a threat to regional peace and security, the Kyodo news agency reported.

South Korea's presidential National Security Office convened an emergency security meeting following the first launch and assessed its impact on national security, the presidential office said.

The government called on Pyongyang to "immediately cease" its ballistic missile launches, describing Sunday's firings as a "grave act" that violated UN Security Council resolutions.

The launches came eight days after North Korea fired multiple short-range ballistic missiles towards the East Sea as part of what it later described as a joint firepower drill.

That exercise involved long-range artillery and missiles, with the weapons "hitting the targets with 100 per cent accuracy", state media reported.

North Korea accused "hostile forces" of seeking to end the country's nuclear program during this week's General Conference of the International Atomic Energy Agency (IAEA).