Pyongyang, North Korea - North Korea fired a suspected intermediate-range ballistic missile on Sunday, Seoul's military said, days after Pyongyang staged live-fire exercises near the country's tense maritime border with South Korea.

"Our military detected one suspected intermediate-range ballistic missile launched from the Pyongyang area towards the East Sea at around 14:55 (12:55 AM ET)," Seoul's Joint Chiefs of Staff said in a statement, referring to the body of water also known as the Sea of Japan.

The missile flew 621 miles, the JCS added, saying that authorities in Seoul, Washington and Tokyo were analyzing the specifications.

"We strongly condemn the latest missile launch by North Korea as it is a clear provocation that seriously threatens peace and stability on the Korean peninsula," it said.

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Japan's coast guard also confirmed a suspected missile launch by North Korea, citing information from the country's defense ministry, and warning vessels to take care.

North Korea's last missile test was of a Hwasong-18 solid-fuel intercontinental ballistic missile (ICBM), which it fired into the East Sea on December 18.

The apparent test comes days after North Korea conducted a series of rare live-fire drills near its maritime border with the South, prompting counter-exercises and evacuation orders for some South Korean border islands.

Leader Kim Jong-un earlier this week branded Seoul his "principal enemy" and warned he would not hesitate to annihilate South Korea, as he toured major weapons factories.

Relations between the two Koreas are at one of their lowest points in decades, after Kim enshrined the country's permanent status as a nuclear power into the constitution and test-fired several advanced intercontinental ballistic missiles.

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Last year, Pyongyang also successfully put a spy satellite into orbit, after receiving what South Korea claimed was Russian assistance, in exchange for arms shipments for Moscow's war in Ukraine.

At Pyongyang's year-end policy meetings, Kim threatened a nuclear attack on South Korea and called for a build-up of his country's military arsenal ahead of armed conflict that he warned could "break out any time".