SEOUL - The Republic of Korea's (ROK) military apologized Monday for firing at a civilian jet two marines mistook as a warplane of the Democratic People's Republic of Korea's (DPRK).

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The two marines attempted to shoot down what was actually a passenger jet owned by Asiana Airlines, a major ROK carrier, which was on its regular flight route early Friday morning. No damage occurred.

The incident stirred up concerns over a possibility of recurrences, and the military copped criticism over the weekend for its recent changes in military rules that allow soldiers to take action before reporting to superiors.

The military offered an official apology for the incident Monday, while defending the marines who were guarding an island off the western port city of Incheon.

"We apologize for causing worries," Colonel Lee Bung-woo, a spokesman at the Joint Chiefs of Staff, told reporters in a press briefing. "The military will seek measures to prevent recurrences by strengthen training for soldiers' on distinguishing warplanes and civilian jets, he added.

The incident came at a time when relations between the two Koreas remain at their lowest ebb over two deadly incidents last year.

Seoul blames Pyongyang for torpedoing its warship and shelling an inhabited border island, which altogether killed 50 South Koreans.

Pyongyang has repeatedly denied its involvement in the sinking of a warship and claimed the shelling was provoked by a military drill between Seoul and Washington near a disputed sea border. It has refused to apologize for any of the incidents.

The two Koreas remain technically at war with each other after the 1950-53 Korean War ended with a ceasefire, not a permanent peace treaty.