SEOUL, South Korea  South Korea would launch a pre-emptive conventional strike against the North if there were clear indications of an impending nuclear attack, the South Korean defense minister said Wednesday in Seoul, even as both countries were holding talks about improvements at their jointly operated industrial park.

The comment by the defense minister, Kim Tae-young, reconfirmed the South Korean military’s stance on the possibility of a nuclear strike by the North, ministry officials said.

But it also marked another exchange of tough talk between two militaries.

Last Friday, North Korea’s National Defense Commission threatened a “holy war to blow away” the South, denouncing Seoul over unconfirmed news reports that the South has recently drawn up contingency plans for a potential collapse of the government in Pyongyang.

“A nuclear attack from the North would cause too much damage for us to react,” Mr. Kim said, speaking at a security seminar on Wednesday. “We must detect signs, and if there is a clear sign of attack, we must immediately strike. Unless it’s a case where we would sustain an attack but still could counterattack, we must strike first.”