Description:North Korea threatened on Friday (January 25) to attack rival South Korea if Seou joined a new round of tightened U.N. sanctions, as Washington unveiled more of its own economic restrictions following Pyongyang's rocket launch last month. In a third straight day of fiery rhetoric against regional powers, the North directed its verbal onslaught at its neighbor, saying: "'Sanctions' mean a war and a declaration of war against us."(1:27)