REUTERS
In this photo provided by the U.S. Navy, a Standard Missile-3 (SM-3) is launched from the Aegis cruiser USS Shiloh (CG 67) during a joint Missile Defense Agency, U.S. Navy ballistic missile flight test off the coast of Kauai, Hawaii, in this June 22, 2006 file photo. (AP Photo/U.S. Navy Photo)
WASHINGTON -- The United States is shifting warships into position to track and possibly defend against a planned North Korean rocket launch while urging Pyongyang to cancel its second such attempt this year, the head of the U.S. Pacific Command said on Dec. 6.