White House press secretary Jay Carney urged North Korea's leadership to "choose the path of peace" Thursday after reports Pyongyang had ordered missiles to its east coast.
Carney would not confirm the missile movements or say that the reports suggested North Korea was more likely to undertake military action.
"I would simply say that we're monitoring both the actions taken by and the statements made by the North Korean leadership," Carney said. "And we're also taking prudent measures to respond to that activity and to those statements."
On Wednesday, the United States announced it was deploying a missile defense system to Guam in response to North Korean threats.
In a statement carried by the North Korean state news agency on Thursday, the country's military warned, "the moment of explosion is approaching fast."
“The U.S. had better ponder over the prevailing grave situation," the statement, reported by The New York Times, continued.
Still, most security analysts do not believe that North Korea is serious about launching a military attack on the United States or South Korea. The White House again emphasized that the actions were part of a "regrettable, but familiar" pattern of behavior.
North Korea has taken a series of provocative steps in recent weeks after the United Nations imposed new economic sanctions in response to a nuclear test conducted in February. In addition to the missile movements, the North Koreans have blocked South Korean access to a joint economic zone, severed diplomatic relations with the Seoul, and declared a "state of war."
In addition to moving the missile defense system into the region, the United States has responded by positioning ships off the Korean Peninsula and performing a series of military exercises with warplanes near the Korean border.