Criticism was also expressed by a more skeptical team of plasma experts assembled by the Condon Committee, all of whom rejected Klass's plasma theory as unscientific. Since that time, theories evoking similar phenomena with widely differing modes of generation have been proposed by commentators such as Michael Persinger, Terence Meaden, Albert Budden, and Paul Devereux. In 1999 the MoD Project Condign report proposed that "Unidentified Aerial Phenomena" (UAPs) comparable to the plasmas originally advocated by Klass (but as amended by Devereux and Randles) may represent a viable explanation for some UFO events. Therefore, while his original concept was discredited, it has been adapted by others, and in this regard Klass is regarded as a pioneer of this approach.