Republic of Korea police on Monday prevented activists from sending anti-Pyongyang leaflets into the Democratic People's Republic of Korea, which had threatened to respond with a "merciless" military strike.

Analysts said both the ROK and the DPRK showed restraint over the issue, which is now not likely to escalate.

The ROK's decision reflects its desire to avoid a stability-threatening confrontation with the DPRK, said Huang Youfu, an expert on Korean studies at the Minzu University of China.

Police officers stand guard to block trucks containing anti-DPRK leaflets on a road in Paju near the demilitarized zone, ROK, on Monday. Seoul has banned activists from launching propaganda leaflets to the DPRK after Pyongyang threatened to attack. Ahn Young-Joon / Associated Press

He said there probably won't be any further confrontations between the ROK and the DPRK before the ROK presidential election in December.

Anti-DPRK groups in the ROK had planned to launch balloons carrying 200,000 propaganda leaflets criticizing Pyongyang's political system. The launch would have taken place on Monday morning from Imjingak Park on the border near the town of Paju, about 60 km north of Seoul, the Yonhap News Agency reported.

But the activists were stopped on their tracks by a roadblock of police vehicles and security personnel who refused to let anyone approach the area.

"It's for security reasons. ... The activists have been blocked from entering the site and will not be able to launch balloons from the park," a ROK police official said.

It was not immediately clear where the decision to block the propaganda exercise came from, although senior police and military officials had met with local government officials in the border area on Sunday.

There has been no response from the DPRK over the failure of the activists, but Pyongyang's army on Oct 19 threatened a "merciless military strike" on the park if the leafleting operation went ahead, and warned local residents to evacuate the area.

"The surrounding area will become targets of direct fire," the army said in a statement on the website of DPRK's Korean Central News Agency.

The DPRK has threatened similar action in the past, but Friday's statement was unusually strong with its specifics on the time and location, coupled with the evacuation warning.

ROK troops were on high alert, and Yonhap News Agency reported the deployment of additional artillery and tank units to forward border positions.

ROK President Lee Myung-bak has taken a hard-line with the DPRK during his five years in office, and the decision to ban Monday's event took some by surprise, the agency said.

"Stability is the number-one priority for Seoul right now," said Yang Moo-jin, an expert on DPRK studies in the ROK, citing the closeness of December's presidential poll as a likely factor.

"I think the president felt that if he let tensions further escalate, he would see his political legacy tarnished at the end of his term and be blamed for leaving a diplomatic burden on the incoming administration," Yang told AFP.

Huang, the Chinese expert, said Seoul's decision shows that it has the desire to ease tensions with the DPRK, and the ROK's attitude toward the DPRK might not be so hard-line after the presidential election because the ROK's president candidates are more moderate than Lee on the issue of DPRK relations.

He added that the plan of the activists, most of whom were DPRK defectors, would have brought tensions or even triggered a crisis over the Korean Peninsula if they had followed through.

Glyn Davies, the US special representative for DPRK policy, called on Pyongyang to give up its stability-threatening behavior, while commenting on the issue during his visit to Beijing.

AFP-China Daily