The Special Inspector General for Afghanistan Reconstruction says the United States may be spending too much on natural gas in Afghanistan.

For the project, the U.S. Department of Defense tasked the Task Force for Stability and Business Operations with constructing a compressed natural gas filling station for automobiles in Afghanistan, spending $43 million.

"The main purpose of the project was to demonstrate the commercial viability of CNG for automobiles in Afghanistan as part of a broader effort to take advantage of Afghanistan's domestic natural gas reserves and reduce the country's reliance on energy imports," SIGAR explains in his report to U.S. Defense Secretary Ash Carter.

SIGAR went on to add that a similar construction project in Pakistan, also a compressed natural gas filing station, came at a cost of $500,000. According to SIGAR, the TFBSO did not conduct a feasibility study, or consider any potential obstacles or broader objectives prior to beginning construction.

"One of the most troubling aspects of this project is that the Department of Defense claims that it is unable to provide an explanation for the high cost of the project or to answer any other questions concerning its planning, implementation, or outcome," SIGAR added.

The Special Inspector General for Afghanistan Reconstruction, a position held by John F. Sopko, oversees the various reconstruction programs implemented by the U.S. Department of Defense in Afghanistan following the U.S.-led coalition invasion of the country.