SEOUL, June 8 (Xinhua) -- The Democratic People's Republic of Korea (DPRK) test-fired multiple projectiles believed to be ground-to-ship cruise missiles Thursday morning into its eastern waters, South Korea's Joint Chiefs of Staff (JCS) said.

The short-range surface-to-ship cruise missiles were launched from the city of Wonsan on DPRK's east coast in the morning, the JCS said in a statement.

The missiles flew about 200 km into the DPRK'S eastern waters. South Korea and the United States were jointly analyzing details on the test-launches.

The South Korean militaryhas strengthened surveillance and vigilance in preparation for additional DPRK provocation, while maintaining full defense preparedness, the JCS said.

The DPRK projectiles were not ballistic missiles. Under UN Security Council resolutions, Pyongyang is banned from testing any ballistic missile technology.

The test-firing by the DPRK came as the U.S. military dispatched nuclear-powered aircraft carriers to waters off the Korean Peninsula.

The test-launches were immediately reported to South Korean President Moon Jae-in right after being detected, according to local media reports.

Pyongyang has conducted missile test-launches five times since Moon took office on May 10.