South Korean Defense Minister Lee Jong-sup has apologized for a failure to shoot down North Korean drones that crossed the military demarcation line between the two countries.

Five unmanned aerial vehicles on Monday went into South Korean airspace. South Korean military attack helicopters and other aircraft attempted to bring them down, firing over 100 shots. The drones are said to have flown back home or vanished from South Korean radar.

Lee on Wednesday apologized for the failure during a session of the national defense committee in parliament, citing past drills as insufficient and promising to strengthen the country's anti-drone capabilities.

Some South Korean media reported that President Yoon Suk-yeol expressed anger after being briefed by Lee on the incident. Criticism of the military's response is growing in the country.

The military announced that it will conduct an air-defense drill on Thursday in haste. The drill will be based on a scenario of North Korean drones flying into the South's airspace.