[T]here had been chilling incidents in which the SWORDS combat bot had swivelled round and apparently attempted to train its 5.56mm M249 light machine-gun on its human comrades.
[Though declared ready for duty in 2004,] concerns about safety kept the robots from being sent [to the] battlefield. The machines had a tendency to spin out of control from time to time.
So the radio-controlled robots were retooled, for greater safety. [...] A three-part arming process — with both physical and electronic safeties — is required before firing. Most importantly, the machines now come with kill switches, in case there's any odd behavior.