A Congressionally created oversight body is urging the temporary suspension of U.S. plans to deliver two C-130H Hercules transport planes to the Afghan Air Force.

U.S. Cargo planes already delivered to the Afghan Air Force are under-utilized, the U.S. Air Force had previously cautioned against the plan, and withholding the planes would save U.S. taxpayers money -- as much as $45.5 million per aircraft, the Special Inspector General for Afghanistan Reconstruction John F. Sopko said in a letter to U.S. Defense Secretary Chuck Hagel and Afghanistan-connected generals.

"Action taken now could save substantial expenditures."

SIGAR was created to provide independent oversight of Afghanistan reconstruction projects and activities. It conducts audits and investigations to promote efficiency and effectiveness in reconstruction programs and to guard against waste and fraud.

The United States has committed about $103 billion for Afghanistan reconstruction and aid between 2002 and June of last year.

The Department of Defense decision to supply Afghanistan with four former U.S. Air Force C-130 transport aircraft coincides with the collapse of Afghanistan's procurement of 16 Italian-made C-27 aircraft. The contractor for the aircraft was unable to provide adequate maintenance support, leaving the planes idle on the ground, according to news reports. The Air Force, which had spent $600 million on the C-27 program for Afghanistan, scrapped the aircraft project and promised Afghanistan the Lockheed Martin-made Hercules as replacements.

Two have been delivered. A third is set for delivery next month and the last by the end of the year.

"During our audit of U.S. support for the AAF to determine its capability to absorb additional equipment, we became aware of concerns regarding the C-130 program," Sopko wrote. "First, we could not determine why DOD (the Department of Defense), in order to provide airlift of medium weight loads to the AAF, decided to provide four C-130s rather than different quantities or types of aircraft.

"Although the decision was made in January 2013 to purchase four C-130s, the AAF's requirement for those aircraft had not been updated since March 2010. Second, we analyzed flight data for the two AAF C-130s currently in Afghanistan and found that they are being underutilized, which raises questions about whether additional aircraft are truly needed.

"Lastly, during my visit last month, I was informed about support problems associated with training, spare parts, and maintenance for the two C-130s currently in the inventory," he said.

In its review, SIGAR said the U.S. Air Force had raised concerns that the C-130s would be too complex and costly for the Afghan Air Force but the Department of Defense still directed the Air Force to provide the aircraft.

"... I suggest that, pending a review of the AAF's medium airlift requirements and its ability to fully utilize the C-130s currently in the inventory, DOD delay delivery of additional C-130s," Sopko wrote. "If DOD's review indicates additional C-130s are unnecessary, DOD should not provide them."