North Korea fired around 500 artillery rounds toward the maritime border with South Korea in the West Sea on Monday as part of a training exercise, and around 100 of them fell south of the sea boundary.
The South responded by lobbing some 300 artillery rounds from K-9 self-propelled howitzers that fell north of the Northern Limit Line and scrambled fighter jets to patrol airspace around the West Sea islands.
It was the first time since the shelling of Yeonpyeong Island in November 2010 that North Korea fired artillery rounds south of the NLL and the first time since the 1950-53 Korean War that the North and South fired at each other across the sea border.
But the North in a rare move notified South Korea through a naval hotline on Monday morning that it would conduct artillery drills along its western coast. The North fired coastal artillery and multiple-launch rocket systems from 12:15 p.m. until 3:30 p.m.
The North also deployed gunboats armed with 122 mm multiple-launch rocket systems while larger 240 mm caliber MLRS as well as 100 mm and 130 mm coastal artillery fired rounds into the West Sea.
Seoul responded by firing around 300 shells from K-9 self-propelled howitzers.
A military officer here said, "We followed our rule of engagement to mount a three-fold response against a North Korean provocation," which was adopted after the North's shelling of Yeonpyeong Island in November 2010. The officer added South Korea "did not strike North Korean coastal artillery positions since the North did not fire rounds at South Korean land."
The Air Force scrambled F-15K fighter jets equipped with SLAM-ER air-to-surface missiles to fly around the West Sea islands.
The North fired the artillery rounds in eight separate bursts, though the last six after the South Korean response were aimed at the northern side of the NLL, according to the Defense Ministry.
This shows that the other two bursts were aimed precisely at the southern side.
On March 27, the Navy seized a North Korean fishing boat in the same waters after it crossed over the NLL near Baeknyeong Island. The Navy returned the North Korean fishing boat six hours later but North Korea protested noisily. The North Korean military threatened to retaliate against what it called "barbaric acts" by South Korea, while the [North] Korean Central News Agency on Sunday quoted a military spokesman as threatening to "blow up" Baeknyeong Island.
Defense Ministry spokesman Kim Min-seok said, "The latest artillery drills were planned provocations and appear to be aimed at testing the South's willingness to protect the NLL."
The military here has raised the alert for all troops and increased monitoring for further provocations like missile launches and infiltration attempts across the heavily-fortified border.
The UN Command in a telephone message to North Korea on Monday afternoon proposed talks between senior officers from both sides.