In this first decade of the 21st Century, most of the major aircraft producing nations are introducing advanced fourth plus and fifth generation combat aircraft into service. With UAV (Uninhabited Air Vehicle) developments benefiting from a technology revolution over the past decade and a half, some nations are now turning their attentions to the development and fielding of UCAV (Uninhabited Combat Air Vehicles), which would be tasked with a number of missions including precision strike against highly protected targets. The main players in this field include a European consortium and the United States. The latter has already deployed converted General Atomics RQ-1A Predator UAV armed with anti-armour missiles operationally in Afghanistan and Iraq with varying degrees of success. The vulnerability of the slow flying Predator is being addressed with purpose designed UCAV's being developed for the USAF and USN under the J-UCAS ( Joint-Uninhabited Combat Air System) program. This includes a number of aircraft programs including the current flying of the Boeing X-45A and Northrop Grumman X-47A. Both companies are developing prototypes of operational vehicles including the Boeing X-45C for the USAF and the Boeing X-46 and Northrop Grumman X-47B for the USN for operations from Aircraft Carriers. The X-45A has been flying for a number of years and was followed into the air by the X-47. Both programs are described in detail as are the forthcoming operational variants, which are much larger than the technology demonstrators. The advantages and disadvantages of removing the human from the aircraft are looked at as are the possibilities for large scale UCAV operations being co-ordinated in the next decade.