US Army officials remain divided on using unmanned aircraft systems (UAS) for the re-supply mission despite a recent move by the US Marine Corps to immediately deploy an interim system.

Although army aviation officials are monitoring the USMC's activity, they have made no move to add cargo re-supply to the four approved mission areas for UAS, which are surveillance, target designation, strike and communications relay.

"We really see [unmanned re-supply] as a niche mission," said Col Jeffrey Kappenman, the army's capabilities manager for UAS.

"We have manned platforms that perform that mission very well," added Kappenman, who briefed reporters on 5 May at the Army Aviation Association of America convention.

He said the army has asked: "Do we already have something available? Do we already have something doing it? And from the army's perspective I think the answer is yes."

Col Brian Diaz, the army's capabilities manager for lift, said he agreed with Kappenman's conclusions. Nonetheless, he said the idea should not be ruled out.

"We are interested. That's the short answer," Diaz said

Until the USMC issued a solicitation last month, cargo re-supply had remained one of the few airborne mission areas performed exclusively by manned aircraft.

Several UAS manufacturers have offered to fill the void. Lockheed Martin has teamed up with Kaman to offer an unmanned K-Max helicopter called the Burro+, which has demonstrated its capability at USMC and Army sites since last year.

Tim Owings, the army's deputy programme manager for UAS, has previously said the army believes there is a legitimate role for UAS to deliver emergency medical and ammunition supplies to troops under fire. It is more difficult to justify the cost to operate unmanned aircraft for routine re-supply flights, Owings said.

The USMC is soliciting for an unmanned aircraft that can haul up to 9,072kg (20,000lb) on a 241km (150mi) round-trip. The system must be able to deploy to a combat area by February.

Besides the Burro+, Northrop Grumman plans to offer the Northrop Grumman RQ-8B Fire Scout. The US Special Operations Command (SOCOM) also plans to propose the Boeing A160T Hummingbird.

Meanwhile, Piasecki Aircraft has proposed concepts for futuristic unmanned aircraft dedicated to the cargo re-supply mission.