North Korea warned of "strong physical counter-measures" against its neighbor, South Korea, over U.S.-backed sanctions recently passed by the U.N., only a day after warning of rocket launches and nuclear missile test targeting the U.S.
The statement comes after North Korea's main ally, China, warned it could pull its aid if North Korea doesn't drop plans for its third nuclear test.
"Sanctions mean war," a statement carried by North Korea's official Korean Central News Agency said.
"It's not the first time they've made a similar threat of war," said Ryoo Kihl-jae, a professor at the University of North Korean Studies in Seoul. "What's more serious than the probability of an attack on South Korea is that of a nuclear test. I see very slim chances of North Korea following through with its threat of war."
"I see this as their way of testing the water," said Narushige Michishita, a North Korea expert at Tokyo's Graduate Institute of Policy Studies. "North Korea will probably never be able to defeat the United States in a war. But they are getting stronger."
Experts say North Korea's threats of war are overblown, but warn that another nuclear test is probable.
"There has been a tendency to underestimate what North Korea can do in the space and missile field, and possibly with technology in general," U.S. nuclear expert Jeffrey Lewis wrote recently on his Arms Control Wonk blog.
Anonymous officials caution that due to underground testing, the U.S. may not know much before a third nuclear tests takes place.