The Defense Ministry has expressed regret over failing to promptly notify civilians of a surge to the Imjin River’s water level that has left at least three dead.

The ministry’s spokesman, Won Tae-jae, told reporters Monday that the military installed a digital device in 2002 that detects water levels. Won said that although the military is not obligated to inform local governments on changes in water levels, the recent incident made clear the need to introduce such a system.

A joint exercise involving the private sector, government and the military to defend against water attacks from the North is currently in place. But Won said the program omits local governments and that his ministry will now seriously consider revising the scope of the program.

According to the Defense Ministry, South Korean and U.S. military officials are trying to determine whether North Korea intentionally discharged the 40 million tons of water from its Hwanggang Dam.