North Korea designated guided missile bases on South Korea's frontline islands as virtual targets during its amphibious landing exercise in the East Sea last Friday, a Seoul official said Sunday.
"We have found that Spike missile units on Baengnyeongdo and Yeonpyeongdo islands were included in the striking targets for the landing exercise, which was carried out off the eastern coastal city of Wonsan with North Korean leader Kim Jong-un observing the drills," said the official, declining to be named.
"This indicates that the North intends to first incapacitate South Korea's missile units and then make a surprise amphibious landing on the border islands to occupy them."
The South has recently deployed to the border islands its Israeli-made Spike missiles, with a range of around 20 kilometers.
The missile is capable of launching precision strikes on the North's coastal artillery hidden in mountain caves and tunnels.
The North's official Korean Central News Agency unveiled a photo in which North Korean leader Kim Jong-un is looking at an exercise plan including a mission to launch an attack on the Spike missile units.
During the landing exercise, the North mobilized a 1,800 ton Romeo-class submarine, a fire support vessel with 122 mm multiple rocket launchers, hovercrafts and other naval vessels.
It also deployed transport aircraft for special commandos and several cannons.
The submarine fired a live torpedo into the sea, Seoul officials explained, saying that it is unusual for the North to fire a live one during an exercise.
Seoul officials said that the North appeared to have arranged the maritime drills in time for Chinese President Xi Jinping's visit to the South to draw attention.
"Its decision to carry out the maritime drills in the East Sea indicates that the North did not intend to provoke China seriously," a Seoul official said, requesting anonymity.
The North is known to have some 20 Romeo-class submarines, 40 Sangeo-class 300 ton submarines and 10 Yeoneo-class 130 ton submarines.
In 2010, a mini-submarine from the North torpedoed the South Korean corvette Cheonan, killing 46 sailors.