South Korea's defense minister instructed his troops on Tuesday not to hesitate to act immediately if they are attacked by North Korea, as he toured the western inter-Korean border wrought with tension after Pyongyang threatened to fire if provoked.

"During an operation, don't ask whether to shoot or not. Report after taking action first," Kim Kwan-jin said during his visit to the First Army Corps, which oversees the tourist zone of Imjingak that the North on Sunday threatened to shoot at, officials said.

Kim's comments, relayed by the Ministry of National Defense in Seoul, are in response to long-running criticism that the military has been slow to react to armed provocations by North Korea.   

The criticism heightened in November last year when the North bombarded a South Korean island and killed four people, leading to the resignation of then Defense Minister Kim Tae-young. 

"Persistent discussions are needed to predict the types of provocation the North may mount," Kim Kwan-jin said, calling on commanders to mobilize their imaginative powers to foresee attacks.

On Sunday, North Korea also threatened to turn Seoul into a "sea of fire," arguing the joint U.S.-South Korean military exercises that kicked off this week are aimed at toppling its regime.

It also said it would fire at Imjingak if South Korea continues to send anti-Pyongyang leaflets in balloons across the border from there, raising already high tensions between the sides.

The 11-day combined Key Resolve/Foal Eagle exercises, purely defensive in nature according to their organizers, began Monday. The war games mobilize tens of thousands of troops from both South Korea and the United States, allies that fought together against the North in the 1950-53 Korean War.

The war continues to this day as it ended in a truce rather than a peace treaty. On Tuesday, South Korean President Lee Myung-bak renewed his offer of talks with the North, urging the communist regime to take steps to show it is regretful of past provocations.

(Yonhap News)