According to MW Cooper, DELTA, or DELTA FORCE, is the designation for the specific arm of the NRO which is especially trained and tasked with security of UFO related projects.
Most sources agree that Delta force, e.g. is the unit that provides security at Area 51 and other high security complexes.
Information that was leaked from the Pentagon and published on the Serpo site (www.serpo.org) in August 2006 claims there is a PROJECT DELTA.
It allegedly is a highly classified project to develop methods to extract specific material from alien spacecraft.
This project is attempting to take materials from known alien artefacts and determine the exact makeup of these materials. It would have been launched, or rather first tested, in 2002.