The Japanese government has condemned North Korea's latest round of missile launches.

Japan's Defense Ministry says two missiles were fired around 3:29 and 3:45 a.m. on Wednesday. Both flew east for about 550 kilometers before falling into the Sea of Japan.

Japanese Defense Minister Hamada Yasukazu said, "Both ballistic missiles fell outside Japan's exclusive economic zone east of the Korean Peninsula. They may have flown in an irregular trajectory. Analysis is still underway."

The launches mark the 13th time this year that Pyongyang has fired ballistic missiles or projectiles using ballistic missile technology.

They came a day after Seoul and Washington met to discuss extended nuclear deterrence and a US nuclear-powered submarine capable of carrying ballistic missiles equipped with nuclear warheads arrived in South Korea for the first time in four decades.

A Japanese government official says the missile launches were likely in response to those efforts to deter Pyongyang.

Kim Yo Jong, the sister of North Korean leader Kim Jong Un, has issued several threatening statements recently.

She said the July 12 launch of the new Hwasong-18 intercontinental ballistic missile was just the start of the country's military offensive.