The North's firing of a submarine-launched cruise missile is seen in this file photo carried by North Korea's official Korean Central News Agency, Jan. 29. Yonhap

North Korea fired several cruise missiles off the west coast Tuesday, the South Korean military said, just two days after it test-fired submarine-launched cruise missiles from the east coast.

The Joint Chiefs of Staff (JCS) said it detected the North's launch at around 7 a.m. from its west coast. It did not specify the number of missiles.

"While strengthening our monitoring and vigilance, our military has been closely coordinating with the United States to monitor additional signs of North Korea's provocations," the JCS said in a text message sent to reporters.

It marks the third cruise missile launch in a week.

On Sunday, North Korea test-fired a newly developed submarine-launched strategic cruise missile, named the "Pulhwasal-3-31," off its east coast, just days after the strategic cruise missile was tested for the first time on Wednesday last week.

Military officials believe the unusually rapid pace of cruise missile tests was aimed at enhancing the performance of the new weapons system.

North Korea claimed the submarine-launched Pulhwasal-3-31 flew for approximately two hours Sunday and hit preset targets, but the South Korean military speculated the North may have exaggerated the flight time.

"The flight time of the cruise missiles launched today flew longer than the ones launched on Jan. 28, which are believed to be flying at a normal range," a Joint Chiefs of Staff official said on the background.

The North first test-fired the Hwasal-1 cruise missile in September 2021, and launched several Hwasal-1 and -2 cruise missiles presumed to be capable of carrying tactical nuclear weapons last year.

The normal flight range of Hwasal-1 is estimated to be around 1,500 kilometers, while Hwasal-2 is presumed to have a range of about 2,000 kilometers. Hwasal means "arrow" in Korean, and Pulhwasal means "fire arrow."

The cruise missiles add threats to the South Korean air defense system in addition to sophisticated ballistic missiles with varying ranges, warheads and launch platforms.

Experts say the submarine-launched cruise missiles could pose a serious threat to South Korea's air defense system if perfected as they are harder to detect and shoot down due to their low-flying altitude and precision strike capabilities. (Yonhap)