North Korea has threatened to open fire on South Korean territory if anti-North leaflets are sent over from its southern neighbour.
A coalition of groups comprising North Korean exiles and human rights activists said they intend to go ahead with the plan to send giant balloons on Monday containing 200,000 leaflets criticising North Korea's government.
The country’s state news agency KCNA said that if leaflets were dropped a "merciless military strike by the Western Front will be put into practice without warning".
It said it would target a tourist area in the border city of Paju, a few kilometres from the demilitarised zone that separates the two countries if the launch went ahead.
In response, South Korea’s Defence Minister Kim Kwan-jin said the country would launch a counter-strike at the source of any attack.
"If that were to happen, there will be a perfect response against the source of the attack," Mr Kim was quoted by Yonhap news agency as telling a parliamentary committee.
North Korea shelled a South Korean island almost two years ago, causing civilian deaths.
In 2010, the North was widely blamed for sinking a South Korean navy ship, although it denied responsibility.
KCNA frequently carries anti-South Korean rhetoric, although a specific threat to an exact area has been rare in recent months.
"The KPA (Korean People's Army) never makes any empty talk," KCNA quoted military commanders as saying.
Pak Sang-hak, a North Korean exile who defected to the South 12 years ago, said: "We had similar threats last year and they did not stop us before and this is not going to stop us this time."
Mr Pak and his colleagues plan to put 1,000 $1 notes in the leaflets inside plastic bags.
They say the US dollars are prized by the impoverished people of North Korea.