South Korea lodges protest against North Korea's artillery drill

South Korea on Tuesday lodged a formal protest with North Korea over its recent artillery drill on an island near the maritime border between the two estranged neighbors.

The protest was sent via the inter-Korean military communication line, South Korean Defence Ministry spokesperson Choi Hyun-soo told reporters.

Choi said that the drill was conducted on November 23, Efe news reported.

The military exercise was carried out on the Changrin islet, located in the Yellow Sea around 15 km (nine miles) north of the western maritime divide, around the same time when North Korean leader Kim Jong-un visited a military unit stationed there.

A day after the drill was reported by the North Korea media on Monday, Seoul expressed its displeasure and said that the exercise was done in violation of a bilateral agreement on reducing military tensions.

The agreement was signed by Kim and South Korean President Moon Jae-in during the summit between the two in Pyongyang in September last year.

"We made it clear that its drill represents a violation of the Sep. 19 inter-Korean military agreement. We strongly urge the North to fully abide by the agreement and stop taking such moves again," Choi said.

Changrin, located around 130 km northwest of the South Korean port city of Incheon, is very close to the Northern Limit Line (NLL), whose legitimacy is disputed by Pyongyang on grounds that it was mapped by Seoul and Washington unilaterally after the end of the Korean War (1950-53) and favours the South.

Those waters have been the site of repeated conflicts between the naval forces of the two countries around islands such as Yeonpyeong or Daecheong which, since 1999, the year Pyongyang toughened its stance against the NL, has resulted in the death of over 100 soldiers from both sides.

North Korea's recent maneuvers highlight the deteriorating inter-Korean relations following a thaw in ties last year.

The lack of progress of denuclearisation talks with the United States, especially in terms of lifting sanctions or reviving cooperation projects between the two Korea countries, has led the regime to adopt an even more hostile stance towards Washington and Seoul.