SEOUL, South Korea — North Korea on Monday accused the South’s government and news media of slandering its leadership and threatened "special actions" by the military.

North Korea has regularly threatened to attack the government of President Lee Myung-bak of South Korea. In recent weeks, its threats have become harsher and more specific, prompting some analysts to warn that North Korea’s new leadership under Kim Jong-un might instigate a military provocation as part of its effort to establish Mr. Kim’s authority at home and boost his negotiating leverage with the United States.

On Monday, the North Korean military said it would act "soon" and named its targets, including the government of President Lee and several South Korean newspapers and television stations.

"The special actions of our revolutionary armed forces will start soon to meet the reckless challenge of the group of traitors," the North Korean military command’s "special operation action group" said in a statement carried by the North’s state-run Korean Central News Agency. "They will reduce all the rat-like groups and the bases for provocations to ashes in three or four minutes, in much shorter time, by unprecedented peculiar means and methods of our own style."

The Defense Ministry in Seoul stuck to its policy of not reacting to what it considers North Korean propaganda, but repeated that the South Korean military and its American allies were ready to cope with any provocation from the North.

The mutual criticism of the two Koreas has grown harsher since North Korea defied international pressure and launched a rocket on April 13 in a failed attempt to put a satellite into orbit.

Mr. Lee called the launch a waste of money that could have been used to buy food for the North Koreans. Last week, he also advised "the young leader in the North" to abandon his country’s collective farm system to resolve its food problem. South Korea also unveiled a new cruise missile capable of hitting targets anywhere in the North.

North Korea staged mass rallies of soldiers and workers calling the Lee government "a group of rats" - an extremely offensive phrase in Korean culture -- and vowing to destroy it.

The risk of North Korea stoking animosity and tension has grown  as the country faces deepening sanctions following its failed rocket launch, said Yang Moo-jin, a professor at the University of North Korean Studies.

"They use brinkmanship to grab the attention of the United States and China," Mr. Yang said. "Now, there is a higher possibility that the North Koreans will act."

So far, none of the North’s recent threats has translated into an armed provocation, partly because the North has concentrated on political events at home, such as party and parliamentary meetings earlier this month that completed Mr. Kim’s official ascension to supreme power, said Cheong Seong-chang at the Sejong Institute in South Korea.

"Now that all of these events are over, North Korea appears to be turning its attention toward the outside world and preparing for a provocation against South Korea," Mr. Cheong said.

Mr. Cheong warned that South Korea must prepare for North Korean provocations, such as hacking of government and news media Web sites and even bio-chemical attacks. Mr. Yang said North Korea’s actions  would be limited to provocations that target the government, but not the South Korean public.

South Korean officials, including President Lee, have recently warned that North Korea might attempt provocations to influence the outcome of South Korea’s presidential election in December.

In a paper released over the weekend, Choi Jin-wook, an analyst at the government-funded Korea Institute for National Unification Studies, warned that Mr. Kim’s less-than-solid control on power and the elite’s competition to prove their loyalty amid an unfolding political purge make the decision-making in Pyongyang more unpredictable. Recent reshuffles in Pyongyang have been marked by the rise and fall of key officials.

"If Kim Jong-un does not control the North’s characteristic brinkmanship from overheating amid the elite’s loyalty drive, we will see provocations," Mr. Choi said.