North Korean leader Kim Jong-un paid a visit to the front-line artillery unit responsible for the country’s 2010 deadly bombardment of a South Korean island, extolling service members as heroes and telling them never to tolerate enemy aggression, state media said Saturday.

The visit to the unit on the North’s border island of Mudo near the tense western sea border came days before South Korea and the United States are to launch their annual joint exercise, Ulchi Freedom Guardian. The computer-assisted exercises, set for Aug. 20-31, will involve some 56,000 South Korean troops and about 30,000 U.S. soldiers.

“He solemnly declared that if the enemy dares recklessly preempt firing and even a single shell drops on the territory of the DPRK, the KPA should lead the battle to a sacred war for national reunification, not confining it to a local war on the southwest region,” Pyongyang’s Korean Central News Agency said in an English-language dispatch.

“He also ordered it to turn the west sea into a graveyard of the invaders,” it said.

DPRK stands for the North’s official name, the Democratic People’s Republic of Korea, and the KPA refers to the North’s armed forces, Korean People’s Army.

The North’s unit shelled the South Korean border island of Yeonpyeong in November 2010, killing two civilians and two soldiers. It marked the North’s first attack on South Korean soil since the end of the 1950-53 Korean War, though the sides have fought naval skirmishes.

The communist nation claimed at the time that it acted in self defense in response to a joint military exercise between South Korea and the United States in waters near the western sea border.

The region has been a source of military tensions, as Pyongyang does not recognize the boundary.

Kim said the area “is not only biggest hotspot on the Korean Peninsula but a very sensitive area on which the world’s attention is focused and where the interests of many countries are intermingled,” according to the KCNA.

The young leader, who rose to power after his father Kim Jong-il died in December, accused the South and the U.S. of “threatening peace and stability of not only the DPRK but of the region and the rest of the world” with “provocative war drills in those waters of the sea.”

“He ordered the servicepersons of the detachment to be vigilant against every move of the enemy and not to miss their gold chance to deal at once deadly counter-blows at the enemy if even a single shell is dropped on the waters or in the area where the sovereignty of the DPRK is exercised,” the KCNA said.

Kim proposed to award the artillery unit “the title of hero” and the “title of heroic defense detachment” for demonstrating the “mettle” of the country’s armed forces during the 2010 battle, and expressed great satisfaction with the unit’s combat posture, the KCNA said.

“The enemy troops on Yonphyong (Yeonpyeong) Island recklessly fired shells at the islet without knowing from where the deadly blows were dealt and they were hit hard by the telling shells fired by the service personnel of the detachment here with towering hatred,” Kim said during the visit, according to the KCNA.

Kim gave the service members a pair of binoculars, an automatic rifle and a machine gun as gifts, expressing the expectation and belief that they “would register laudable feats in the sacred struggle for defending the country,” the KCNA said.

Earlier, Kim also visited the defense detachment on the nearby island of Jangjae.

Analysts said Kim’s visit to the units appears aimed at raising the morale of the military after sacking army chief Ri Yong-ho in July, while demonstrating his grip over the armed forces and his standing as supreme commander.

“I think he visited the front-line units to boost the fallen morale of troops after the purging of top military official Ri Yong-ho, citing the UFG exercises as a pretext” for the visit, said Chang Yong-seok, a researcher at the Institute for Peace and Unification Studies, Seoul National University.

“I think the visit is also aimed at tightening his grip over the military by demonstrating courage as leader by visiting the dangerous far front-line,” he said. (Yonhap News)