North Korea fires a Hwasong-18 solid-fuel intercontinental ballistic missile (ICBM), July 12, in this photo released by the North's official Korean Central News Agency. Yonhap

North Korea fired two ballistic missiles into the East Sea late Monday, the Joint Chiefs of Staff (JCS) said.

"Our military detected two ballistic missiles North Korea fired from areas near Pyongyang into the East Sea at 11:55 p.m. on the 24th and at midnight of the 25th," it said.

Both missiles flew about 400 kilometers before falling into the sea, it added.

The military is still analyzing the North's latest missile launch to determine the exact type of the missiles fired, according to the JCS.

The North's latest missile launch comes as a nuclear-powered U.S. submarine, USS Annapolis, arrived at a naval base in South Korea's southern island of Jeju as part of efforts to bolster joint deterrence against North Korea's evolving threats.

North Korea fired two ballistic missiles into the East Sea on Wednesday, followed by multiple cruise missile launches on Saturday. (Yonhap)