From Halopedia, the Halo wiki
Paul Huphy Russel was a human politician and the Secretary of Defense in 2552. That year, during the Battle for Earth, Russel issued a general appeal to the youth of New Mombasa asking them to join their local "freedom fighter brigade" to fight the Covenant. His propaganda-laced message can be seen on view screens throughout downtown New Mombasa.
He is most likely named after Bungie employee Paul Russel. Unlike the other signs found in the Metropolis, the sign with Russel's message is destructible and will explode violently, similar to the signs seen in the Halo 2 E3 Demo.
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