Russian transport aircraft delivered the first installment of Iranian-made combat drones to Russia in August. The shipment, part of a larger order totalling hundreds of drones, included Mohajer-6 as well as Shahed-series models. Although they are considered among Iran's most capable models, the drones have already faced technical and mechanical problems, according to U.S. officials. The terms of the deal were unclear, but an adviser to Iran's government said no money had yet been exchanged for the equipment.