By the end of 2016, the Afghanistan Air Force is due to have 86 Russian-made Mi-17 helicopters. Most of them will have been purchased by the United States from Rosoboronexport, the same state weapons exporter that continues to arm the Syrian government of President Bashar Assad.

Congress is not pleased — but has struggled to do anything about it.

The Pentagon says there is no better, cheaper helicopter than the Mi-17 to operate in Afghanistan's desert expanses and high altitudes, and that it is the aircraft the Afghans know best.