The U.S. Army has retired its Hunter unmanned aircraft system after 20 years of service.

The medium-altitude RQ-5 Hunter, developed by Israel Aerospace Industries and manufactured by TRW -- now part of Northrop Grumman -- saw service in the Balkans and early in the Iraq war, providing U.S. military commanders with intelligence and surveillance information.

It is being replaced by the MQ-1C Grey Eagle from General Atomics.

"Although the Hunter UAS had performed extremely well during rotation exercises, it proved itself for the first time in contingency operations as an invaluable and reliable intelligence asset to commanders at all levels." The Army said. "The Hunter flew more flight hours than any other NATO reconnaissance platform."

Retirement of the aircraft was marked recently with a final flight and a ceremony at Fort Hood in Texas.

The Army is transferring MQ-5 Hunters at Fort Hood to government-owned, contractor-operated units supporting U.S. operations overseas.

The Grey Eagle UAS that will be operated by the 15th Military Intelligence Battalion at Fort Hood beginning next year can fly for 25 hours, achieve speeds up to 167 knots and reach altitudes up to 29,000 feet.