ⓒYONHAP News

South Korea and North Korea exchanged warning shots early Monday morning along their disputed Yellow Sea border region. Amid heightened military tensions, a North Korean merchant vessel first violated the border, according to the South Korean military. North Korea has a different account. 

The two Koreas took turns firing warning shots in the western coast early morning Monday.

According to the South Korean Joint Chiefs of Staff, its Navy fired 20 warning shots as a merchant vessel from North Korea did not leave South Korea's maritime territory after violating the Northern Limit Line, or NLL, despite repeated warnings.  

The General Staff of the North's Korean People's Army(KPA) via KCNA said its coastal defense units fired ten rounds of artillery warning shots toward its waters, claiming that a South Korean warship first crossed its maritime border, which it says is drawn some six kilometers south of the NLL.

South Korea's Joint Chiefs of Staff said North Korea violated the 2018 inter-Korean military accord by launching artillery shots.  

[Kim Jun-rak - spokesperson, S. Korean Joint Chiefs of Staff (Korean-English)]  

"With regards to the firing today, the South Korean military detected the North firing ten artillery shells from South Hwanghae Province into the NLL maritime buffer zone in the West Sea. The fact that the North fired against our military's normal operational measures against a North Korean merchant ship that violated the NLL, is a clear violation and provocation of the September 19 military agreement."

While urging North Korea to immediately halt provocations, the JCS said South Korea will boost its military readiness in the area. 

[Name undisclosed, S. Korea Defense Ministry (Korean-English)]  

"The Navy will conduct joint exercises [with the U.S. Navy] in the West Sea from today until the 27th as part of the national defense drill. This training will be conducted as a large-scale maritime live-action exercise to improve the ability to carry out joint naval operations in preparation for enemy provocations and establish military preparedness." 

The warning shots did not lead to clashes this time. However, amid the heightened military tensions on the Korean Peninsula, the maritime border disagreement in the west coast now is a more likely source of military conflict between the two sides. 

The North's 2010 shelling of Yeonpyeong Island and its torpedo sinking of a South Korean navy ship took place in the area after two naval clashes in 1999 and 2002.