The pilotless drone aircraft has become key to current conflicts such as Afghanistan.
Pilots flying drones remotely by computer link from thousand of miles away are replacing pilots flying aircraft over combat zones.
As well as use by the military, drones have also been used extensively by the CIA to attack suspected al-Qaeda and Taliban leaders in Pakistan and other countries.
Critics have said there have been many civilian casualties as a result of these attacks.
Drones are also likely to play a major role in Western strategy for containing al-Qaeda and the Taliban after military withdrawal from Afghanistan.
And many countries around the world are rushing to acquire these new weapons.
But increased of drones raises all kinds of ethical as well as military questions.
How far can technology take over combat? In an updated version of a programme first broadcast last year, Stephen Sackur investigates a secretive and controversial change in how we wage war.
Producer: Chris Bowlby.