South Korea will ramp up its readiness against possible provocations by North Korea ahead of the sixth anniversary of the North's shelling of a western border island in 2010, military officials said Sunday.

As North Korean leader Kim Jong-un recently visited front-line units near the border with the South, Seoul's Joint Chiefs of Staff does not rule out the possibility of a shelling by the North against the South's Yeonpyeongdo Island or other northern border islands in the West Sea. The North's artillery bombardment of Yeonpyeongdo took place on Nov. 23, 2010, resulting in four deaths.

"Just before the 2010 shelling, the North Korean leadership paid a visit to artillery units stationed on islands near the western sea border (with the South). The then North Korean leader Kim Jong-il was accompanied by his son Jong-un," a JCS official said in a text message sent to reporters.

In the same year, North Korea also sank a South Korean warship that resulted in the deaths of 46 sailors.

This year, the military has closely watched North Korea's artillery units' activities in the border areas as they have noticeably enhanced their presence by placing 122 mm multiple rocket launchers there, the JCS said.

In an article carried by the North's official Korean Central News Agency, Pyongyang said, "(Kim) inspected the outpost on Kali Islet and the defense detachment on Jangjae Islet in the West Sea.

"(Kim) approved the newly worked out combat document of the plan for firepower strike at Yeonpyeong Island. He also indicated tasks for rounding off combat preparations and increasing combat capability of the outpost," the KCNA said in the English dispatch.

Kali and Jangjae Islets are located 4 kilometers north of Yeonpyeong Island and 6.5 km northeast of the island, respectively.

"If provoked, we will firmly react to any type of provocations by the North," the JCS said. (Yonhap)