The South Korean military conducted a live-fire drill near the inter-Korean border on the Yellow Sea, a heavily-guarded area, on Friday.

According to the country’s defense ministry, the latest exercise was carried out to check the preparedness of South Korean forces against possible provocations by the North, Yonhap, a South Korean news agency, reported. The naval drill, which lasted for two hours, was part of the ongoing Hoguk (defense of nation) exercise, which kicked off last week, involving nearly 330,000 troops and 60 fleets. The latest 12-day drill, which comes amid growing tensions due to threats from North Korea, is the largest ever in terms of scale, Yonhap reported.

“The patriotic training is to improve unity among all three armed forces and the Marine Corps, and it has been conducted yearly since 1996,” a defense ministry spokesman said, in a statement. “This training, in particular, focuses on enhancing the connection between headquarters of operations and establishing the military preparedness posture against enemy provocation. It is conducted along the entire 155-mile front line at all military levels.”

Last week, South Korea’s Maritime Counter Special Operation Force (MCSOF) conducted “intensive training” of its naval forces near the Northern Limit Line, a maritime demarcation line in the Yellow Sea, disputed by the two neighbors.

“The MCSOF operation is to destroy enemy special operations forces and covering forces who try to land on our beach,” according to a statement on South Korea’s defense ministry website. The ministry also said that various military equipment such as 7,600-ton class Aegis destroyers, convoys, patrol frigates, guided-missile patrol gun boats and submarines, were part of the training exercise. 

Last week, North Korean officials had warned of “a great war of justice” after South Korean troops had reportedly fired shots to stop a North Korean patrol near the military demarcation line. Last month, both countries fired shots at each other, after the North Korean military shot down balloons carrying anti-Pyongyang propaganda leaflets launched by South Korean activists.