The Inquisition had sent out an urgent warning that they believed the Necrons were attempting to infiltrate imperial positions with spies and all Guardsman must be extremely vigilant against possible Necron agents.
"Nonsense! " bellowed Imperial Guard general Samuel Klein. "How could those mechanical monstrosities possibly pass themselves off as human?! The very thought of a Necron spy getting into this base is absurd! "
Then he sat down in his new chair to plan the next offensive.