North Korea fired multiple unidentified cruise missiles on Tuesday at 7 a.m. into the sea off its west coast, South Korea's military said, the third time Pyongyang has tested cruise missiles in less than a week.
South Korean and US intelligence authorities were closely monitoring the situation and analyzing the details of the launch, it said.
The launch comes amid a rise in tension on the Korean peninsula and follows a barrage of cruise missiles fired by Pyongyang off its east coast on Sunday.
Sunday's launch was a test of the new submarine-launched cruise missiles (SLCM) dubbed "Pulhwasal-3-31" and leader Kim Jong Un supervised the test, North Korean state media KCNA reported on Monday.
South Korea's JCS said last week that it believes the firing of "Pulhwasal-3-31" was to test upgrades of existing missiles' capabilities.