Egypt identified the Greeks as mercenaries they could use against the Persians. They used the Greeks, both Athenians and Spartans to good effect and developed a master plan to persuade the Greeks to fight against the Persians out of self interest apparently without Egyptian involvement. The technique they used was to penetrate Greek society and inject anti- Persian propaganda into their psyche. Their aim was to distract and defeat the Persians.
In the process triggered the birth of what we call civilisation.