Chief of the U.S. Pacific Command, Adm. Robert Willard, said Tuesday the ship is offloading equipment at Nampho, a port city west of the capital, Pyongyang.
The U.S. and North Korea agreed in October to restart the search for thousands of American service members, a sign of easing tensions between the wartime enemies.
The program is due to begin formally on March 1, with a U.S. advance team arriving in Pyongyang later in the month.
The search was suspended in 2005 during tensions over North Korea's nuclear program. The U.S. cited misgivings about the security of its personnel.