The Northern Limit Line is a disputed maritime border between North and South Korea. It extends from the west coast of Korea where it curves northward, effectively isolating five remote South Korean-controlled islands.

A painting is seen around the site where a shell landed during the 2010 North Korean attack on the island of Yeonpyeong. In 2010 North Korea fired multiple shells onto the island killing four people, including two civilians. Reuters

Baengnyeong, which is closer to Pyongyang than Seoul, is a heavily militarised island whose residents live in constant fear of possible clashes between two armies.

Another island, Yeonpyeong, was shelled by North Korean rockets and artillery in November 2010 when South Korean marines were conducting artillery drills on the island.

In subsequent years, the South Korean government has increased its military presence on the islands. Cliff tops are adorned with cruise missiles capable of striking Pyongyang, and the beaches are lined with barbed wire, soldiers, and mines.

The line was drawn up at the end of the 1950-53 Korean War and North Korea does not recognise it. The two sides are still technically at war as the conflict ended in a mere truce, not a treaty.

In March this year, an unmanned drone crashed onto Baengnyeong Island. The drone measured about seven feet in length and was equipped with a small camera. Aerial photos of several South Korean cities and the presidential palace were discovered on the camera.

A South Korean military inquiry suggested that the unmanned aircraft was flown by North Korea to conduct reconnaissance missions.