Seoul: North Korea fired an unidentified projectile toward the sea to the east of the Korean peninsula, South Korea's Joint Chiefs of Staff said in a statement on Saturday.
South Korea's Joint Chiefs of Staff said that the projectile was a suspected ballistic missile.
Later, Japan's coast guard said that North Korea may have fired a missile. The office of Japan's prime minister said it was a suspected ballistic missile.
South Korea's security council said it condemned the launch and that it would closely monitor the North's nuclear and missile-related facilities.
South Korea's military said the launch came from a location near Sunan. Sunan is a northwestern district of the North Korean capital Pyongyang and hosts the city's international airport.
The airport has been the site of previous launches, including the testing of a spy satellite system on February 27.
Japanese Defense Minister Nobuo Kishi said that initial assessments suggest that the missile flew 300 kilometers eastward at a maximum altitude of 550 kilometers. The missile then landed in waters between the Korean Peninsula and Japan, according to Kishi.
Jean Lee, a fellow of the Washington-based Wilson Centre, said that the "timing of North Korea's missile testing may seem odd to us, given the global focus on Ukraine."
"But it makes perfect sense in North Korea, where scientists are focused on perfect new weapons for Kim to show off at a big military parade in mid-April," she added.
The apparent test comes four days ahead of South Korea's presidential election.
This would be the ninth launch this year.
In January, North Korea threatened to abandon a self-imposed moratorium on testing long-range and nuclear weapons.
Pyongyang said on Monday it conducted a test of "great significance" towards developing a reconnaissance satellite. A day earlier, Seoul said it had detected a ballistic missile launch.