South Korea on Tuesday said it had lodged a formal protest with North Korea over its recent coastal artillery drills, revealing the exercise had been staged on the ninth anniversary of the North’s bombardment of Yeonpyeong island.

In a regular briefing, Ministry of National Defense (MND) spokesperson Choi Hyun-soo said the South had taken countermeasures in response to the North’s live-fire exercise, conducted near the inter-Korean maritime border on Changrin island.

“We strongly remonstrated the North this morning about its coastal artillery firing exercise through a communication line in the western district,” Choi said.

The South verbally lodged the protest with the North through a phone call, she added, through a communication channel on the western coast of the peninsula.

Seoul, Choi added, has also sent a written protest to Pyongyang, though it has not received an immediate response.

The MND also confirmed that the South Korean military had detected signs of the North’s live-fire exercises on Saturday morning.

Spokesperson Choi repeatedly denied claims that the ministry had attempted to conceal related information or delay the release of the news, however.

When asked why the government did not previously reveal that the North had staged military drills on the nine-year anniversary of North Korea’s shelling of Yeonpyeong island, Choi said that Seoul had needed to consider the timing when making an announcement on the issue. The ministry had previously declined to share details.

North Korean artillery shells hit Yeonpyeong island on November 23, 2010, in an attack which resulted in the deaths of two civilians and two South Korean soldiers.

The bombardment represented the first military clash between the two Koreas to result in civilian deaths since the end of the Korean War.

South Korea’s military had still been analyzing the nature of this weekend’s drills, Choi said Tuesday, when North Korean media released footage of the drill.

“We hope there will be no misunderstanding on the issue as we will inform [the public] based on the most accurate analysis of what we have identified,” she said.

South Korea’s Yonhap News Agency on Tuesday reported that the military “had detected signs of North Korea’s firing of coastal artillery in advance and made preparations,” citing an unnamed military official. “We confirmed that the North had fired several shots through various means, including listening to an unidentified sound source.”

The South Korean military analyzed the unidentified sound after detecting it on Saturday morning, another unnamed official told Yonhap.

Following North Korean state media’s reporting on the drill on Monday, the official said the military had assessed that the source of the sound was coastal artillery being fired on Changrin island.

When asked about the South’s preparedness in the face of further provocative military actions from the North, spokesperson Choi on Tuesday said that Seoul was “fully prepared” take measures in response to Pyongyang’s violation of the inter-Korean military agreement.

The South Korean defense ministry, she continued, will press the North to pursue the “faithful implementation” of that agreement through means including verbal notification and public statements.

“In addition, we will make continuous reconnaissance and surveillance activities so that the North can faithfully implement the military agreement of September 19 and we can check its implementation,” Choi said.

Monday saw Seoul formally accuse Pyongyang of having violated last year’s inter-Korean military agreement by conducting coastal artillery drills in what was intended to be a military buffer zone.

Expressing “regret” at the move, the defense ministry urged the North to “immediately halt” military actions which could heighten tensions along the inter-Korean border.

Under the terms of the inter-Korean military agreement, signed in Pyongyang last September, the two Koreas committed to ending military exercises in the air, land, and sea, aimed at the other along the Military Demarcation Line (MDL) as of November 1, 2018.

Both sides also specifically agreed to end “all live-fire and maritime maneuver exercises within the zone north of Deokjeok-do and south of Cho-do” on the western coast of the peninsula. Changrin island, where the weekend’s exercise took place, is located south of Cho-do.

Under the terms of last year’s agreement, too, the two Koreas must also “install covers on the barrels of coastal artilleries and ship guns and close all gunports” within that buffer zone.

Edited by Oliver Hotham

Featured image: KCNA