Any further North Korean artillery strikes south of the maritime boundary between North and South Korea will be met with shelling from the South, the South’s defense minister said Tuesday.

On August 9, North Korea fired more than 100 artillery rounds toward the Northern Limit Line, the sea border between the two Koreas set after the Korean War. Ten of those rounds fell south of the line, according to news reports from South Korea. At that time, the South did not return fire but sent warning messages through military channels to the North.

“Under the previous rules of engagement (near the NLL), we’re supposed to send warnings through hotlines and not return fire unless the North fires additional shots,” Defense Minister Kim Tae-young told a parliamentary committee on Tuesday, according to a report from The Korea Times.

New rules call for an immediate military response, but still require the North to be warned that the South Korean shelling is coming.

"If North Korea fires artillery rounds south of the NLL, we will respond by firing toward north of the NLL," the Yonhap news agency quoted Kim as saying.

Tension between the Korean Peninsula neighbors has been heightened since the sinking of a South Korean warship, the Cheonan, in March.

South Korea and an international inquiry found a torpedo fired by a North Korea submarine responsible for the sinking, in which 46 South Korean sailors died. The North has denied any role in the loss of the Cheonan.

South Korea has since staged military exercises - including anti-submarine drills with U.S. forces - which the North has called a provocation. It was shortly after South Korean naval maneuvers concluded on August 9 that the North fired its artillery barrage.

Last Friday, the U.S. military said it will conduct new anti-submarine exercises with South Korea next month.