Autonomous weapons systems (AWS) are for most people akin to science fiction. Although fully autonomous weapons systems do not yet exist, recent rapid progresses in artificial intelligence compels us to think about the potential impact of this weapon on the conduct of war, international security and international stability. This paper starts by reviewing what artificial intelligence is all about, its recent progress and then looks at the likely impact of AWS on strategic stability. It argues that AWS will likely be very destabilizing for international stability because they favour the offensive. It follows that strategies of pre-emption are likely to emerge to thwart the use of AWS.