North Korea fired a ballistic missile into its eastern sea, South Korea's military said on Sunday.
The launch came a day after South Korean officials said they detected signs that Pyongyang was preparing to test a missile designed to be fired from submarines.
Japan also confirmed the launch and said it reached a maximum altitude at 50 kilometers (30 miles) and may have flown on an irregular trajectory.
Japan's Defense Minister Yasukazu Hamada said the missile fell outside Japan's exclusive economic zone.
'Threat to the peace'
"North Korea's action represent a threat to the peace and security of our country, the region and the international community and to do this as the Ukraine invasion unfolds is unforgivable," Hamada said.
North Korea has carried out more than 30 missile tests this year.
The country's leader Kim Jong Un has told his parliament this month that he would never abandon his nuclear weapons and missiles he needs to counter what he perceives as US hostility.
A barrage of missile tests by Pyongyang in June had prompted the United States and South Korea to respond with tests of their own.
US aircraft carrier in South Korea for first time since 2017
The latest test comes as the US nuclear-powered aircraft carrier USS Ronald Reagan and its strike group arrived in South Korea forjoint military exercises.
South Korea's President Yoon Suk-yeol, who vowed on the campaign trail to get tough with Kim, has ramped up Seoul's joint drills with the US.
The arrival of the carrier group is part of a push to have increased US nuclear-capable assets operate in the area to deter North Korea.
South Korea's navy said that its joint training with the Americans is meant to showcase military readiness and "the firm resolve by the Korea-US alliance for the sake of peace and stability on the Korean Peninsula."
US Vice President Kamala Harris was also due in the region next week.