The missiles flew about 400 kilometers (249 miles) before splashing down into the sea with no reports of damage.
North Korea has fired multiple short-range ballistic missiles toward its east coast, South Korea and Japan said, the second such test in a week.
The missiles were launched from Kaechon, north of the capital Pyongyang, at around 6.50am on Wednesday (2150 GMT on Tuesday) and flew about 400 kilometres (249 miles) northeast, South Korea's Joint Chiefs of Staff (JCS) said, without specifying how many were fired or where they landed.
“North Korea’s missile launch is a clear act of provocation that seriously threatens peace and stability on the Korean Peninsula, and we strongly condemn it,” the JCS said in a statement.
Japan also confirmed the launch and the coast guard said North Korea fired at least two ballistic missiles.
The test comes days after North Korea's foreign minister met with top Russian security official Sergei Shoigu in Moscow.
The two countries, which have been heavily sanctioned, have grown closer in recent months and analysts say the latest evidence could be linked to North Korea's alleged illicit arms supply to Russia for use in Ukraine. Pyongyang has denied sending weapons to Moscow.
“Given the resurgence of the war in Ukraine and Shoigu's recent visit to North Korea, the latest missile launches could be for export to Russia,” Yang Moo-jin, president of the University of North Korean Studies in Seoul, told AFP news agency.
Pyongyang fired multiple short-range ballistic missiles last Thursday, the first such launch in more than two months, which it later said was a test of a new 600mm multiple launch rocket system.
It was the country's first major test since early July.
The United States, South Korea and Ukraine, among other countries, have accused Pyongyang of supplying rockets and missiles to Moscow in exchange for economic and military assistance.
A report released last week by Conflict Armament Research used debris analysis to show “that missiles produced this year in North Korea are being used” on the battlefield against kyiv.
United Nations sanctions monitors said earlier this year that fragments of a North Korean Hwasong-11 missile had been found after a Russian strike in Kharkiv in January.
Wednesday's missile launches also came days after the isolated country released the first images of its uranium enrichment facility.
North Korea conducted its first nuclear test in 2006 and has been subject to UN sanctions ever since.
