Rodong Sinmun, newspaper of the ruling communist party, said the "war deterrent" -- its term for the nuclear programme -- was created to avert moves by "US imperialists" to launch a nuclear war and invade the North.
"It is also meant to protect South Korea, too, with warm compatriotism," the paper added in an analysis which took aim at the Grand National Party (GNP).
"The GNP group is raising a hue and cry over the war deterrent of the north which protects them too, while uttering no bad word about the nukes of the US which threaten the nation," it said.
The GNP has savaged the Seoul government's engagement policy with the North since the October 9 nuclear test, and called for tougher sanctions on Pyongyang.
"The GNP gentry is a group of traitors utterly indifferent to the fellow countrymen and the destiny of the nation," the newspaper said.
It took particular issue with GNP calls for two inter-Korean projects -- the Mount Kumgang tourist resort and the Kaesong industrial estate -- to be shut down after the test. The Seoul-financed projects have earned the North almost one billion dollars since 1998.
"These traitors are desperately insisting on suspending the tour of Mount Kumgang and the project of the Kaesong industrial zone, icons of undertakings for national reconciliation and co-operation," said the analysis carried by the official Korean Central News Agency.
The South Korean government announced Monday it will not take any new steps under UN sanctions to punish North Korea for its test and will not join a US-led initiative to inspect cargo to and from the North.

Copyright AFP (Agence France-Presse), 2006