It goes without saying that South Korea has to deal resolutely with any unprovoked security threat from North Korea. It has every right to retaliate against a North Korean attack many times more, as it promises. Failure to do so would make the South Korean military look like a paper tiger, encouraging bolder hostilities from the North.

But North Korea’s latest threat to launch an artillery strike against the Imjin Pavillion in Paju, Gyeonggi Province, was a different situation. It was a response to what it apparently perceived to be a serious provocation from the South.

On Friday, North Korea said it would target the pavilion, one of South Korea’s northernmost tourist attractions, for an artillery strike if South Korean conservatives, including defectors from the North, were allowed to send anti-communist leaflets over to North Korean territory, as they had often done before.

In what they regard as human rights-promoting activities, the activists have sent anti-communist leaflets in balloons, often together with $1 bills and daily necessities, aiming at turning North Korean residents against their oppressive regime. But the cornered mouse, as the maxim goes, could attack the cat.

On Friday, North Korea threatened to launch a “merciless military strike” against the South Korean target if the leaflets were dropped on Monday as planned. As if to demonstrate its resolve to make good on its threat, the North reportedly put its artillery in place for an attack.

A deadly exchange of fire was averted when the South Korean military and police blocked the activists from entering the pavilion. In defiance, however, they denounced the South Korean government for surrendering to the North Korean threat and vowed to continue to send leaflets to the North.

The activists, and anyone else for that matter, have every right to pursue what they regard as a worthwhile mission insofar as it does not pose any inconvenience, not to mention danger, to others.

But they are urged to exercise self-restraint and abstain from any more risky provocations. The South Korean government will have to step in, if they refuse to toe the line. With Seoul’s metropolitan area placed within the range of the North Korean artillery, they should be reminded that their ill-conceived activities could expose a population of more than 10 million people to an attack by the North.