South Koreans are poised to pay tribute to soldiers killed in North Korea's artillery shelling of a western border island four years ago, officials said Thursday, as tensions continue to run high along the sea border.   

On Nov. 23, 2010, the North fired some 170 rounds of artillery at the front-line island of Yeonpyeong, killing two South Korean marines and two civilians, and wounding 16 others. It was Pyongyang's first artillery attack on South Korean soil since the end of the 1950-53 Korean war.

The Ministry of Patriots and Veterans Affairs said it will hold a memorial mass in Seoul on Sunday to remember their sacrifices and imbue the people with a firm sense of national security.   

During the ceremony to be attended by some 4,500 government officials, soldiers and citizens, Marines and students from the island will perform a number of ceremonies to mark the event. The participants will also watch video footage and military band performances and burn incense for the victims.

On Yeonpyeong Island, residents, together with retired and active service members, are scheduled to host various other ceremonies, including photo exhibitions, on Sunday to remember the victims, the ministry said. 

Despite the loss of life, the Marines say they won the skirmish as they did not back down and responded immediately to the North's artillery. The extent of the damage in North Korea has never been confirmed, with the North denying any casualties on its side.

"I felt like time stopped. But I tried to be sober, and launched shots toward the North with the sole, desperate goal to save lives of my soldiers," Gunnery Sergeant Kim Young-bok said in an interview with Yonhap News Agency. The 28-year-old Marine was in charge of an artillery platoon on Yeonpyeong at the time of the shelling.

"Some of the Marines shed blood in the enemy's attack, but not a single soldier left the scene," he said. "We did win the battle, period."

Kim said he has been trying to teach his subordinates the lessons of the tragic incident and to be fully prepared to counterattack as the North is always ready to provoke.

Four years on, tensions remain high near the western sea border, known as the Northern Limit Line (NLL), the de facto inter-Korean maritime border. The North does not recognize the line, demanding it be drawn further south.

In the latest incident, the two Koreas briefly exchanged fire in the Yellow Sea after a North Korean patrol ship violated the NLL, prompting the South Korean military to fire back. No casualties were reported. 

In response, Seoul has beefed up its military capabilities near the northwestern border islands, establishing the Northwest Islands Defense Command in 2011 and deploying an additional 1,200 troops as well as radar, attack helicopters and rockets.

And it plans to do more.

"We've been pushing to set up a new combat unit in the Yellow Sea region armed with high-speed rigid inflatable boats and landing craft air cushions," an officer of the Marine Corps headquarters said. 

"For enhanced surveillance capabilities, we will set up a system for unmanned aerial vehicles and push for the project to launch aerostats in the border regions," he noted. (Yonhap)