Meh. if you want a really threatening thing, make it cultural. If you want a real "enemy" for the UFP, make it another UFP-like polity that isn't populated by braindead/anachronistic/technophobic/socially-straightnecked people. Make the UFP-like polity technically less-advanced, than the UFP, but due to "more smarts" they actually accomplish more than the UFP. That should be enough to cause a cause a long-overdue crisis of faith in the UFP.
