SEOUL, South Korea — North Korea fired several ballistic missiles into the sea on Monday, South Korea’s military said, hours after South Korean and U.S. troops kicked off their large annual combined drills, which the North views as an invasion rehearsal.

North Korea launched several unidentified ballistic missiles towards the Yellow Sea, according to South Korea's Joint Chiefs of Staff (JCS). The missiles were launched from Hwanghae Province. The JCS assured that they have enhanced surveillance and readiness to cooperate with the United States.

Under UN Security Council Resolutions, North Korea is barred from staging any launches that use ballistic missile technology