The introduction of attack drones into the US military was major change in the way wars are fought, and the US has been keen to maintain their lead in drone technology by dramatically limiting the export of such vehicles, hoping to keep them in the hands of a few choice allies.

It was a notion, but not a successful one, as the growing number of rejections by the US is leading to a surge in sales for Chinese companies who are making a series of military drones of their own, including the Wing Loong, a direct copy of the US Predator drone.

The Chinese drones are comparable, and cheaper, and officials say that a growing number of Chinese-made drones are showing up in air bases across the Middle East, reflecting their growing popularity as an alternative to the much tougher to come by US versions.

US officials are seeing this both as a blow to their policy goal of keeping drone capabilities in the hands of a limited number of states, as well as a long-standing priority to give well-connected US arms-makers an endless number of lucrative export deals.