North Korea is threatening to attack South Korea if Seoul joins a new round of United Nations sanctions.
In a third consecutive day of rhetoric, the North on Friday directed a verbal onslaught at South Korea, saying: "'Sanctions mean a war and a declaration of war against us."
On Thursday, North Korea said it would carry out further rocket launches and another nuclear test.
Further sanctions imposed by the United Nations against North Korea on Wednesday and the United States announced economic sanctions on Thursday on two North Korean bank officials and a company in Hong Kong.
North Korea held a long-range rocket launch on 12 December, sending a satellite into space.
State media on Friday in China indicated that Beijing would decrease aid to Pyongyang if it goes ahead with a nuclear test.
"If North Korea engages in further nuclear tests, China will not hesitate to reduce its assistance," said the Global Times in an editorial.