The Secretary General of the United Nations, Ban Ki Moon, issued a warning on North Korea Tuesday.
Pyongyang, he said, appears to be "a collision course with the international community."
Ban is from South Korea, and was once foreign minister of that nation.
He was speaking after North Korea took the tension back up a notch by announcing plans to re-open a closed nuclear facility at Yongbyon.
That facility by the way had been shuttered in 2007, in exchange for US aid.
But in the text of a speech released Tuesday by North Korea's young leader, Kim Jong-Un, there were no new threats to attack the United States or South Korea.
Joel Wit is a former US negotiator with North Korea.
He says the North's behavior is predictable, from their perspective.
"They feel threatened," says Wit. "And the best defense is offense."
It's all posturing, he says. "They're not going to attack anyone."
But there is a danger of an accidental war. North Korea cannot afford to look weak, because "for the North Koreans, looking weak is almost as good as committing suicide."