In the coming 25 years, the Air Force hopes to have drones take over or assist with more of the types of missions that are currently being conducted by manned aircraft, including search and rescue, inflight refueling and humanitarian assistance. Military officials also believe that advances in technology will allow drones to use “kinetic” and “directed energy” weapons to destroy short-range battlefield missiles.
But, for the time being, the Air Force is reluctant to entrust drones with the mission that we hope never to see happen:
Certain missions, such as nuclear strike, may not be technically feasible unless safeguards are developed and even then may not be considered for UAS [unmanned aircraft systems] operations….Ethical discussions and policy decisions must take place in the near term to guide the development of future UAS capabilities, rather than allowing the development to take its own path apart from this critical guidance.
via Air Force Says Drones Won’t Carry Nukes…For Now.