North Korea fired projectiles into the sea off its east coast, the South Korean and Japanese government reported on Sunday.
South Korea's Joint Chiefs of Staff reported that a projectile believed to be a single missile was launched at around 7:52 a.m. local time (2252 UTC) from North Korea's northern Jagang province.
Later on Sunday, the Joint Chiefs of Staff reported that the projectile had been identified as a medium-range missile that had flown 800 kilometers towards the open sea.
Japan's Defense Ministry and prime minister's office said the weapon was possibly a ballistic missile.
Japan's coast guard issued a maritime safety warning, but there were no immediate reports of damage to boats or aircraft.
Seventh weapons test this year
North Korea has intensified weapons testing recently in the face of stalled diplomacy with the United States.
Sunday's test North Korea's seventh weapons test this year.
North Korea fired two short-range ballistic missiles into the sea on Thursday.
In a ruling party meeting chaired by Kim Jong Un on January 20, North Korean officials discussed resuming nuclear and long-range missile tests. North Korea has been observing a self-imposed moratorium on these tests since 2017.
North Korea also flight-tested two purported long-range cruise missiles on Tuesday, which it is not barred from testing by United Nations sanctions.
Leif-Eric Easley, a professor at Ewha University in Seoul, told the AP news agency, "North Korea is launching a frenzy of missiles before the start of the Beijing Olympics, mostly as military modernization efforts."
"It wants to remind Washington and Seoul that trying to topple it would be too costly," he added.
The US called on North Korea to refrain from further destabilizing acts, the US Indo-Pacific Command said in a statement.
The statement said the command assessed that the test did not pose an immediate threat to US territory, personnel or allies.
South Korea's national security council condemned the launch as a violation of the resolutions and a challenge to international peace efforts.
Japanese government spokesperson Hirokazu Matsuno said "the ballistic missile launch and the ones before it are a threat to our country, the region and the international community."
"This series of launches violate UN resolutions and we strongly protest this action by North Korea," Matsuno added.