North Korea has fired four anti-ship missiles into the sea east of the Korean Peninsula, probably to demonstrate its "precise targeting capability".
The projectiles, launched near the eastern port city of Wonsan, were believed to be surface-to-ship cruise missiles, South Korea's joint chiefs was quoted as saying by CNN Thursday.
"We assess that North Korea intended to show off its various missile capabilities, display its precise targeting capability, in the form of armed protests against ships in regard to US Navy carrier strike groups and joint naval drills," Roh Jae-cheon, a spokesman for South Korea's Joint Chiefs of Staff said.
North Korea has launched 16 missiles in 10 tests so far in 2017, and Thursday's test was the fourth since new South Korean President Moon Jae-in took office in May.
Each test whether succeeds or not but certainly it improves missile technology and finally delivering information that aids North near attaining its aim of developing a missile that could reach the US, analysts state.
The launch follows the move of Moon's government suspending the deployment of a controversial US missile defense system which had strained relations with China and angered North Korea.
The missiles flew about 200 kilometers (124 miles), South Korea's military said. He added the US military was undertaking a more detailed analysis.
"Our military has strengthened surveillance and alertness readiness in cases of additional provocation by North Korean military and is maintaining all readiness posture while we are tracking and monitoring related situation," the official said.
A US defense official confirmed a launch had been detected. However, the Pentagon is unlikely to release a statement as these were not ballistic missiles capable of posing a long-range threat, the official said.