The USS Carl Vinson aircraft carrier made a port call in Guam on Friday in what could be a preparation to take part in an annual joint military drill between South Korea and the United States slated for March, a military source said.

A possible mobilization of the nuclear-powered carrier for the upcoming Key Resolve exercise is aimed at deterring North Korea's growing nuclear and missile threats, it added.

In early January, the Nimitz-class carrier departed from Naval Base San Diego, which is the principal homeport of the US Pacific Fleet for a regular deployment to the Western Pacific, according to the UN Navy.

"The Carl Vinson arrived in a naval base in Guam earlier in the day," the military source said. "The carrier appears to be readying for a new mission."

South Korea is keeping close tabs on North Korea's possible military provocations that may come sometime in March and April when Seoul and Washington hold their annual military exercise.

North Korea is threatening to launch an intercontinental ballistic missile, which would target the US mainland.

Pyongyang has long denounced exercises like Key Resolve as a rehearsal for a northern invasion despite South Korea and the US' assurance of the drill's defensive nature.

The top military commanders of South Korea and the United States recently reaffirmed the two countries' commitment to forming a strong joint defense posture against North Korea's provocations. (Yonhap)