With North Korea's launch of a mid-range Musudan missile believed to be imminent, a U.S. official confirms that the SBX radar has been deployed to the Pacific to assist with tracking the missile if it is launched. That tracking could help bring a missile down if needed.

The Sea-Based X-Band Radar looks like a giant golf ball placed atop a platform that resembles a floating oil rig.

It contains a precise long-range radar that is part of the integrated missile-defense system and helps track launched missiles so they can be brought down by missile interceptors.

With North Korea threatening to launch missiles against the United States, the Pentagon reportedly sent the radar system out to sea April 1 from its home port of Pearl Harbor to assist with tracking a potential missile launch.

The next day, Pentagon spokesman George Little denied that was the case, underscoring that the radar had gone to sea as part of previously scheduled sea trials. "They're undergoing semiannual system checks," Little said. "Decisions about further deployments have not been made to this point."

A U.S. official now says the SBX is no longer undergoing sea trials and "has been deployed to the Pacific for an operational missile-defense mission."

"It's up and running and active," the official said.

U.S. officials believe that at least one Musudan missile transported to North Korea's eastern coast last week is ready for launch and has been fueled.

Defense Secretary Chuck Hagel told reporters Wednesday that the United States "is fully prepared to deal with any contingency, any action that North Korea may take or any provocation that they may instigate."

He said the international community has been very clear that North Korea "with its bellicose rhetoric, with its actions, have been skating very close to a dangerous line." He said their actions and words "have not helped defuse a combustible situation."

He urged North Korea to turn down the rhetoric.

U.S. Pacific Command Adm. Sam Locklear told a Senate panel Tuesday that the United States has the capability to intercept a Musudan missile, but that he would not recommend shooting it down if its trajectory did not pose a threat to the United States or its allies in the region.

With a range of more than 2,000 miles, the Musudan cannot reach Hawaii or the U.S. mainland, although it could reach U.S. bases in Okinawa and Guam.

The U.S. Navy has deployed two Aegis destroyers to the region that are equipped with SM-3 missile interceptors that could bring down a North Korean missile. Both South Korea and Japan have each deployed two similar Aegis destroyers to the waters off the Korean peninsula to provide missile defense.