A U.S. State Department spokeswoman said Thursday the situation did "not need to get hotter," reflecting efforts by the Obama administration to ease its rhetoric and cool tensions.
But the latest developments by North Korea, which has accused the United States of pushing the region to the "brink of war," could signal a missile launch soon, officials have said.
The missile components, U.S. and South Korean officials have said, are consistent with those of a Musudan missile, which has a 2,500-mile range, meaning it could threaten South Korea, Japan and Southeast Asia.
It is believed a missile launch would be a "test" launch rather than a targeted strike.
That is because it appears the North Koreans have only moved the components so far. The United States is waiting to see whether North Korea issues a customary notice to its airmen and mariners to stay out of the region.
Communication intercepts in recent days also seem to show that Pyongyang might be planning to launch a mobile ballistic missile in the coming days or weeks, another U.S. official said.
Wednesday, the United States announced it was sending ballistic missile defenses to Guam, a Western Pacific territory that is home to U.S. naval and air bases. North Korea has cited those bases when listing possible targets for missile attacks.
Pentagon officials, while decrying North Korean rhetoric, said recent announcements of U.S. military deployments in response to belligerent statements by Pyongyang may have contributed to the escalating tensions.
As the bombast reaches a fever pitch, the United States is refining its message. The Pentagon now says it is working to decrease the temperature as it maintains a frank and vigilant stance toward the threats.
Starting Wednesday, North Korea also barred South Korean workers and managers from entering the Kaesong industrial complex, an economic cooperation zone that sits on the North's side of the border but houses operations of scores of South Korean companies.
It also repeated a threat from the weekend to shut down the complex, where more than 50,000 North Koreans work.