The existence of the "Ghost Fleet" was suggested by the agency's experimental Predictive Analytic Machine in December, 2075. P.A.M. analyzed the capabilities of Chinese stealth technology and the efficiency of its intelligence apparatus, and concluded that China would be able to conceal large scale research from American operatives and was 91% likely to conduct large scale experimentation with stealth technologies.
As the United States lagged behind China in stealth technology, merely reverse engineering Hei Gui suits into Stealth Boys without understanding the underlying science, theoretical limits of the technology were unknown. In a subsequent analysis, P.A.M. posited that the "Ghost Fleet," reported by two DIA monitoring stations in November, may indicate that testing of large scale stealth tech applications may have commenced with submersible vessels.
However, when asked to refine the answer and directly establish whether stealth submarines were in service with the Chinese navy, P.A.M. could not reach a conclusive second order approximation, due to limited data and too much variability in the analytical chain. When asked to guess by a general, it promptly shut down. P.A.M.'s first order approximation, establishing macro scale research into stealth technology, was corroborated by an increase in the imports of complex polymers and other key synthetic compounds to Shaanxi Province that previously flew under DIA's radar for over three years. However, the general querying P.A.M. dismissed the idea of stealth subs as "nonsense" and that it was "ludicruous" that the U.S. "heard nothing." The matter was buried, with DIA personnel told to not bother the general unless they have concrete evidence of the fleet’s existence.
The Ghost Fleet is mentioned in Fallout 4.