(CNN) -- The Pentagon should suspend the acquisition of four dozen aircraft for a special Afghan military team because the unit lacks the "capacity to operate and maintain them," a government watchdog audit said Friday.
The agency got thumbs down from the special inspector general for Afghanistan reconstruction for moving forward with a $771.8 million purchase of 48 aircraft for a newly formed entity called the Afghan Special Mission Wing, or SMW.
The audit singled out for criticism a contract to a Russian government agency for acquisition of 30 Mi-17 helicopters, spare parts, test equipment and engineering support "despite our recommendations."
"We maintain that moving forward with the acquisition of these aircraft is imprudent," said Inspector General John F. Sopko in a letter to Defense Secretary Chuck Hagel.
The wing was established in July 2012 to carry out counternarcotics and counterterrorism missions in Afghanistan, but the audit pointed out a range of deficiencies in the program's development that need to be corrected.
In essence, the program still needs to evolve before aircraft purchases are made, the audit said. For example, it said, there are not enough qualified personnel to operate and maintain the crafts, and it's difficult to find literate recruits who don't have links to insurgents or criminals.
And the audit cites examples of "inadequate" Pentagon oversight.
The acquisition and delivery of the aircraft should be tied to development milestones, Sopko said. Major aircraft acquisitions should be suspended until the Afghan government "takes necessary steps to build SMW capacity," and Pentagon oversight of "critical functions" in the program should be enhanced, he said.
"We believe that the purchase and delivery of the aircraft should be contingent on the SMW's achievement of personnel and maintenance and logistics support milestones and indications that the SMW has the capacity to execute its mission and operate and maintain its fleet," the audit said.
"Without an effective support structure, U.S.-funded SMW aircraft could be left sitting on runways in Afghanistan, rather than supporting critical missions, resulting in waste of U.S. funds."