South Korea, Japan and the United States dispatched five Aegis class vessels, including the South's King Sejong the Great destroyer, to track down a rocket North Korea is poised to launch. The missile has apparently been set up at a launch pad in Musudan-ri, North Hamgyong Province.

A South Korean military source on Thursday said Seoul decided to immediately deploy the King Sejong the Great in the East Sea when it became clear the North had set up the rocket. The ship is South Korea's first Aegis class naval vessel and equipped with radar that can track ballistic missiles as far as 1,024 km away.

The U.S. Navy has deployed two of its own Aegis vessels -- the USS Chaffee (DDG-90) and the USS John McCain (DDG-56) -- to track the missile following their participation in joint military drills with South Korea. Japan has also deployed two Aegis vessels in the East Sea -- the Kongo and Chokai -- which are equipped with SM-3 interceptor missiles.

U.S. intelligence officials are apparently finding it difficult to determine whether the rocket is a ballistic missile or a satellite-launch vehicle, since the North Koreans have placed a tarpaulin over the warhead. Intelligence agencies believe the first stage of the missile has a stronger thrust than originally believed, since it was made by combining five to six Rodong missile rockets into one.

South Korea's top nuclear envoy Wi Sung-lak is scheduled to visit the U.S. on Friday to meet with Stephen Bosworth, the special representative for North Korea policy, and Sung Kim, Washington's top envoy to the six-way talks, to discuss North Korea's missile launch. Japan's chief nuclear negotiator Saiki Akitaka is also visiting Washington during that period.