Defense Secretary Chuck Hagel has said "North Korea rhetoric presents real, clear danger, threat to U.S., allies."

This comes with the announcement of the movement of high-altitude missile defense batteries to U.S. bases in Guam, an American territory 2,000 miles southeast of the Korean Peninsula.

Hagel has also maintained open communication with the Chinese military in terms of mitigating the North Korean threat militarily.

Prominent arms analyst Jeffrey Lewis told an Australian think-tank that U.S. troop movements west of the peninsula indicate that a North Korean missile launch is imminent.

From the Lowy Institute for International Policy:

This is unacceptable. The United States, Australia, and other allies appear to be taking important policy decisions on the basis of the imminent deployment of the KN-08 [a North Korean missile]. If this is the case, they should say so directly and provide the basis for asserting the imminent deployment of the KN-08.

Hagel's direct statement comes on the heels of months-long bluster from North Korean leader Kim Jong-un.

The bluster was ostensibly in response to strict U.N. sanctions, a diplomatic action which stemmed from the nuclear test in February.

The placement of missiles in Guam is just one of many recent military mobilizations. An advanced radar rig and two Aegis-class destroyers have sailed to the western Pacific in response to missile movements on the west coast of North Korea.

Also, the Pentagon has plans to put missile batteries in Alaska to mitigate the extended range of North Korea's newest rocket, semi-successfully launched in December. Though analysts doubt the rocket has adequate guidance systems, the notional range is enough to reach Alaska.