Pyongyang carried out a record-breaking blitz of weapons tests last month, including of its most powerful missile since 2017, when leader Kim Jong Un baited then-US president Donald Trump with a spate of provocative launches.

High-profile negotiations between Trump and Kim followed, but collapsed in 2019.

Since then, talks with the US have stalled, and the country is reeling economically from international sanctions and a self-imposed coronavirus blockade.

Pyongyang has doubled down on military development, warning last month that it could abandon a self-imposed moratorium on long-range missile and nuclear weapons tests.

"North Korea fired an unidentified projectile eastward," the Joint Chiefs of Staff said in a statement, without giving further details.

Japan also confirmed Sunday's launch, with a defence ministry spokesman telling AFP that "potential ballistic missile(s)" were fired from North Korea, without specifying how many.

Japan's coastguard issued a warning to vessels about a "potentially ballistic missile possibly launched from North Korea".

North Korea paused its weapons testing during the Winter Olympic Games, likely out of deference to its only major ally China, analysts have said.

But with the international community distracted by Russia's invasion of Ukraine, many analysts had expected North Korea to seize the opportunity to restart testing.

Japan's foreign minister Masayoshi was on live TV speaking about Ukraine when news of North's launch broke.

"This situation in Ukraine is not something that stays just in Ukraine or in Europe. But it could potentially affect the entire world, or Indo-Pacific region or in East Asia in our view," he said.

South Korea has said it will join international economic sanctions against Russia and, as a key US security ally, Seoul is closely watching Washington's response to Moscow's aggression, according to local reports.

- Back to crisis -

North Korea's latest sabre-rattling also comes as South Korea gears up to elect its next president on March 9.

Outgoing South Korean President Moon Jae-in, who repeatedly pursued peace talks with the North during his five-year term, has warned that the peninsula could easily slide back into crisis.

"If North Korea's series of missile launches goes as far as scrapping a moratorium on long-range missile tests, the Korean Peninsula may instantly fall back into the state of crisis we faced five years ago," he said in a written interview with international press, including AFP, this month.

Dialogue between Washington and Pyongyang remains stalled.

Under Trump's successor Joe Biden, the United States has repeatedly declared its willingness to meet North Korean representatives, while saying it will seek denuclearisation.

But Pyongyang has so far dismissed the offer, accusing Washington of pursuing "hostile" policies.

Domestically, North Korea is preparing to celebrate the 110th anniversary of the birth of late founder Kim Il Sung in April, which experts say Pyongyang could use to carry out a major weapons test.

Recent satellite images suggest that the North may be preparing a military parade to showcase its weapons to mark the key anniversary.