A South Korean army's K-9 self-propelled howitzer fires during a military exercise in Yeoncheon near the border with North Korea, August 18, 2016. (Photo by Yonhap via AP)

South Korea has launched large-scale artillery drills near the border with North Korea amid heightened tensions between the two neighbors.
According to South Korea’s military, a total of 300 artillery systems deployed along the border began firing shells simultaneously in multiple directions on Thursday afternoon.
The South Korean army said that there was no sign of any unusual military response by the North.
An unnamed South Korean army official said the number of artillery mobilized in Thursday's drills was the biggest ever, adding that the simultaneous shooting in all major frontline areas was a departure from previous exercises.
The border between the two Koreas is the most heavily fortified in the world.
The two countries occasionally exchange gunfire along the frontier and near a disputed maritime border.
In recent years, South Korea has held several joint military drills with the United States.

South Korea and US Marines run to a position during a joint military drill at a fire training field in the southeastern port of Pohang on July 6, 2016. (AFP photo)

Pyongyang is irked by joint Seoul-Washington military maneuvers, viewing them as direct threats to its security.
Tensions have been flaring in the region since January when North Korea said it had successfully detonated a hydrogen bomb, its fourth nuclear test, and vowed to build up its nuclear program as deterrence against potential aggression from the US and its regional allies.

This undated file photo released by North Korea's official Korean Central News Agency (KCNA) on July 21, 2016, shows a missile fired during a drill by Hwasong artillery units of the army. (AFP photo)

A month later, Pyongyang launched a long-range rocket which it said placed an earth observation satellite into orbit. However, Washington and Seoul denounced it as a cover for an intercontinental ballistic missile test.
​North Korea says it will not abandon its nuclear “deterrence” unless Washington ends its hostile policy toward Pyongyang and dissolves the US-led command in South Korea. Thousands of US soldiers are stationed in South Korea and Japan.