The US 8th Army said its "Shadow-200" unmanned aerial vehicles were airborne for several hours after taking off from a US military base, 40 kilometers (25 miles) north of Seoul.

"The maiden flights ended in success," said a spokesman for the US 2nd Infantry Division, a frontline unit belonging to the 8th Army.

The spokesman declined to give the exact number of the US remotely-controlled surveillance planes deployed in South Korea but said "several" were put into operation.

The new spy plane, already operational during the US-led war in Iraq, is designed to fly for up to five hours, providing "real time, accurate and relevant intelligence of the battle field," he said.

The deployment of the surveillance planes in South Korea is part of an 11 billion dollar US defense build-up plan against North Korea.

The United States said last week it was upgrading its missile defense capabilities in South Korea to the Patriot Advanced Capability-3 (PAC-3) from PAC-2, sparking strong protests from North Korea.

Some 37,000 US troops are stationed in South Korea since the 1950-1953 Korean conflict ended in a fragile armistice, rather than a peace treaty.

WAR.WIRE