South Korean military fired warning shots and issued warnings to expel a North Korean patrol boat that breached the Northern Limit Line (NLL), the de facto sea boundary, on Saturday. The incident occurred a day after North Korea’s missile tests and further raised tensions. 

According to the Joint Chiefs of Staff of South Korea, the North Korean vessel crossed the maritime border around 11am (9pm ET), prompting the warning shots and broadcasts.

“Our military maintains decisive battle posture while monitoring the enemy’s movements in preparation for potential provocations regarding NLL violations by North Korean patrol boats,” the JCS said in a statement on Sunday, as per Reuters.

The JCS reported that a South Korean patrol ship and a Chinese fishing vessel had a minor collision during the operation, but no safety issues arose Only slight injuries were sustained by the South Korean crew due to bad visibility. 

The incursion of North Korea came amid increased tensions over the North’s recent military activities, including the test of a new solid-fuel intercontinental ballistic missile on Friday, which experts say could facilitate missile launches without warning. 

Pyongyang has disputed the NLL, drawn up at the end of the Korean War in the 1950s, arguing that it should be placed further south. In October, both Koreas exchanged warning shots in the western waters, accusing each other of violating the sea border in a region where such confrontations have frequently occurred.

Pyongyang has threatened military action due to the annual springtime exercises carried out by South Korea and the US since March, calling them a rehearsal for nuclear war. 

South Korea’s air force has announced that it will conduct joint drills with the US Air Force and Marines from Monday until April 28. The exercise involves 110 aircraft, including South Korea’s F-35 and F-15 fighters and American F-16 jets and KC-135 aerial refuelling tankers, as well as 1,400 troops from both sides, according to the statement. 

North Korean leader Kim Jong Un recently ordered to strengthen war deterrence to counter what the country called aggressive moves by the United States and South Korea. However, Seoul and Washington claim that their drills are defensive in nature and intended to deter North Korea.