North Korea has a long history of military conflicts, including the Korean War.
Communist leaders in that country have been seen as irrational and out-of-touch with reality and for one history professor, it's enough to take any threat seriously.
North Korea's Kim Jong Un got a lot of the world's attention over the weekend.
The 29-year-old leader said North Korea is in a state of war with South Korea, an American ally.
From his office at Lycoming College in Williamsport, Doctor Robert Larson said the things the North Korean government has been saying are irrational.
"It's still very dangerous. What would concern me more than anything else is whether or not they become prisoners of their own rhetoric," said Larson, a history professor at the college for more than 40 years.
Larson said there are severe socio-economic problems in North Korea and a feeling that if the country does not follow through on threats, it could lose any legitimacy it has.
"You create this kind of situation and you can't all of a sudden say 'Oops, we made a mistake everything's fine,'" he said.
What's the United States' role in all this?
There are American troops stationed in South Korea and the U.S. has deployed fighter jets from Japan to South Korea to take part in military drills.
And for now, the only thing coming out of North Korea, is talk.