The Joint Chiefs of Staff (JCS) said that North Korea fired multiple cruise missiles off its east coast on Sunday, its second such launch in less than a week.

The JCS said that it detected the launch from waters off North Korea's port city of Sinpo in South Hamgyong Province at around 8 a.m., adding that the South Korean and United States intelligence authorities are analyzing the details of the launch.

The JCS said that the military is cooperating closely with the United States to monitor the situation in the North and additional signs of provocation while strengthening surveillance and vigilance.

The launch comes just four days after the JCS detected North Korea's launch of a cruise missile from the west coast. Pyongyang claimed that it fired a new strategic cruise missile called "Pulhwasal-3-31," suggesting it is nuclear capable.

The military has not mentioned whether the latest missiles were launched from the sea, underwater or land, and the North Korean state media has also yet to make an official announcement.

Considering Sinpo is where North Korea's submarine facilities are located, North Korea may be speeding up the development of a weapon system called the submarine-launched cruise missile (SLCM).

Unlike ballistic missiles, it is usually difficult to detect the launch and landing points of cruise missiles because they fly in various directions and low-orbit, forming a figure-8 pattern no matter where they are launched.