South Korean military drills on Monday were conducted without incident despite fiery warnings from North Korea.

Ahead of the drills, North Korea on Sunday issued a warning saying that it woul respond with a “merciless counterstrike.”

Monday’s exercise involved South Korean Marine Corps units stationed on the islands near the northern limit line in the West Sea firing various weapons into South Korean waters. The Marine Corps’ exercise, which involved K-9 self-propelled guns, mortars, Vulcan anti-aircraft guns and attack helicopters, was conducted for two hours from 9:30 a.m.

In addition, the navies of South Korea and the U.S. began a five-day anti-submarine drill in the area.

Although the North Korean forces maintained a heightened readiness for the duration of the exercise, an attack on South Korean territory did not occur.

“North Korea is thought to have maintained heightened readiness posture (during the exercise), but details are not confirmed,” a Joint Chiefs of Staff spokesman said.

“We will continue to hold firing drills for improving readiness posture in the West Sea islands. If the enemy provocation occurs in response to routine exercises we plan to take accurate and swift punitive measures.”

However, with further military drills including the South Korea-U.S. joint exercise Key Resolve scheduled for the month, Seoul’s armed forces plan to closely monitor North Korean movements for the time being.

In preparation against possible North Korean provocations, the South put all artillery units near the border on standby.

In addition, residents of the concerned islands including Baengnyeongdo and Yeonpyeongdo, which was shelled by North Korea in 2010, were evacuated ahead of the marines’ live-fire drill.

The evacuation order was lifted with the end of the exercise.

Although Pyongyang’s military has habitually issued such warnings in response to drills conducted by Seoul and its allies, Sunday’s statement differed in that it warned civilians in the area to evacuate before the drills begin.

“If a military provocation occurs, a merciless counterstrike will begin,” North Korean military’s western command said, according to Pyongyang’s Korean Central News Agency. Pyongyang’s military added that the target area for the drill was in North Korean waters and it will begin a counterstrike as soon as any activity is detected within their waters.

“In relation to this, those living or working on or around the five West Sea islands should evacuate to safe areas before 9 a.m. on the 20th when the provocative firing drill begins.”

By Choi He-suk  (cheesuk@heraldcorp.com)