"North Korea fires unidentified ballistic missile towards the East Sea," Seoul's Joint Chiefs of Staff said, referring to the body of water also known as the Sea of Japan.

Tokyo also confirmed the launch, with the coast guard saying that it involved two ballistic missiles.

Broadcaster NHK said both suspected ballistic missiles appeared to have fallen outside of Japan's Exclusive Economic Zone, citing unnamed government officials.

The tests come as Kim is in Russia with his top military officials, set to meet Putin on Wednesday for talks focused on defence cooperation.

Russia is eager for North Korea's stockpile of artillery shells likely for use in Ukraine, while Pyongyang is looking for help upgrading its antiquated Soviet-era equipment especially for its airforce and navy, experts say.

"Fascinating: a launch without Kim Jong (Un) in the country. A first," US-based analyst Ankit Panda wrote on X.

North Korea has conducted a string of banned weapons tests so far this year, the last one involving firing two short-range ballistic missiles on August 30.