North Korea launched four anti-ship missiles into the Korean Peninsula early Thursday, marking its fourth test in just one month.
The system is created to shoot down short- and medium-range ballistic missiles in the latter stages of their flight as they drop toward their targets.
The missiles were fired from the North Korean eastern coastal town of Wonsan and likely flew about 200km (about 125 miles) with an altitude of about 2km (1.2 miles), South Korea's Joint Chiefs of Staff said in a statement. The projectile, believed to be a Scud-class missile, flew around 450 kilometers before landing in the Sea of Japan, some 300 km off the Japanese islands.
It marked the North's fifth-known round of missile firing since the launch of the South's liberal Moon Jae-in administration in early May.
"All North Korea can earn from provocations like this is global isolation and economic hardship", said Moon.
Seoul "will not take a single step back or make compromises over the issue of national security or the safety of its people", Moon said, according to his spokesman.
Mr Roh said he believed the North was "showing off its capability with various types of missiles and demonstrating its anti-ship precision-strike ability in connection with joint maritime drills involving USA aircraft carrier strike groups".
North Korea's latest launches of several suspected anti-ship missiles were short-range and landed well short of past efforts, but they still served as a defiant message for its enemies that Pyongyang will continue to pursue a weapons program that has rattled its neighbors and Washington.
"North Korea is carrying out carefully calibrated provocations... but restraining from ICBM tests or nuclear explosions which could bring about military retaliations by (US President Donald) Trump", he added.
In Washington, the U.S. missile defense chief voiced worries about the pace of development in the North's missile program.
China, the reclusive regime's sole major ally, has made it clear that a push for talks - and not more sanctions - is its priority.
President Moon Jae-in, left, presides over a National Security Council (NSC) meeting at the Blue House at 2 p.m. Thursday as North Korea fired several short-range anti-ship cruise missiles off its eastern coast in the morning.
Moon, who has said he wants to try to resolve the North's nuclear crisis through dialogue, also has suggested that South Korea must "learn to say no" to Washington.
"It is also expressing displeasure of the arrival of a United States nuclear submarine in South Korea".
The 6,900-ton USS Cheyenne, whose home port is Pearl Harbor, arrived in the South Korean port of Busan Tuesday, as the United States steps up its own muscle-flexing in the region.
THAAD also includes a sophisticated radar that will fit into an overlapping series of U.S. missile defense systems, including Aegis warships operating in the Pacific and Patriot missile batteries deployed in Japan.
Japan's foreign minister Fumio Kishida said after Thursday's launch that Tokyo has not detected any "flying objects" that headed toward Japan or landed inside the country's maritime economic zone.
While not all of this year's launches have been successful, there is growing unease in the region, and increasingly in the U.S., that Pyongyang is making progress in its plan to put a nuclear warhead on an intercontinental ballistic missile.