March 30, 2013 -- North Korea announced Saturday it is in a "state of war" with neighboring South Korea and threatened to shut down the joint industrial area called the Kaesong industrial zone --- one of the only remaining joint ventures between the two Koreas providing the North access to $2 billion in trade a year.
The White House responded to the latest threats by calling for restraint.
"North Korea has a long history of bellicose rhetoric and threats and today's announcement follows that familiar pattern," said Caitlin Hayden, National Security Council spokeswoman. "We remain fully prepared and capable of defending and protecting the United States and our allies."
The Pentagon continues to take every North Korean threat seriously. Recently, plans were announced to increase U.S. ground-based interceptors and early warning and tracking radar.
"We're concerned that their reach in and beyond the region will be extended over time," said a senior defense official. "That's one reason why it's all the more important to show that the United States is committed to our alliances, interests, and personnel in the Asia-Pacific."
On Thursday, B-2 stealth bombers were flown from an air base in Missouri to the Korean peninsula.
Pentagon officials said the show of force was a direct message to the North Korean leader that the U.S. is prepared to protect its allies in the region.
By Friday, North Korea leader Kim Jong Un appeared in front of a map titled "Plans to Attack the Mainland U.S." The map listed targeted states including California, Texas, Washington, and New York.
The leader also signed an order putting missiles on standby. Analysts believe North Korea doesn't have the capability to hit the mainland U.S.
One senior defense official told ABC News that the U.S. has what it needs to respond to the threats.