The attacks on Saudi oil installations have led to speculation that armed drones were involved.
Both the United States and the Saudi authorities say this may well have been the case.
The offensive use of drones or unmanned aerial vehicles (UAVs) has grown significantly in recent years, and nowhere more so than in the Middle East.
So who has them and who has used them in combat?
A new weapon
The first combat use of an armed drone came in October 2001, on the first night of the Afghan War against a Taliban convoy.
Armed UAVs were initially the preserve of a few technologically advanced nations, with Israel and the United States very much in the lead.
Soon a new provider came onto the scene – China, eager to sell its weaponry around the world.
The Chinese have boosted the spread of military drones in the Middle East,…