The Shadow 200 Tactical Unmanned Aerial Vehicles will help the U.S. military to monitor North Korean military activities along the 2½-mile-wide, 155-mile-long Demilitarized Zone between the two Koreas.
The U.S. military said in June that it planned to pull U.S. troops further away from the DMZ, the world's most heavily armed border, but remained committed to defend South Korea against possible North Korean provocations.
Tension on the Korean Peninsula remains high over the communist North's suspected development of nuclear weapons. North Korea often accuses the United States of infiltrating its airspace with spy planes — a claim the U.S. military denies.
The Shadow spy planes are designed to track enemy movements and assess battle damage. The planes were used in the U.S.-led war against Iraq.
"This system gives us a marked advantage over the enemy," said Cpt. Samuel Hall of the U.S. Second Infantry Division. "With the Shadow, we now have the ability to see first, understand first and finish decisively."
The U.S. military will begin flying the vehicles on Friday from a base north of Seoul.
Shadow planes fly at an altitude of between 10,000 feet and 14,000 feet and can carry up to 60 pounds of surveillance equipment.
Washington keeps 37,000 American troops in South Korea — a legacy of the 1950-53 Korean War.