[genericuser]

They will say existing security clearance required, because that greatly speeds up their hiring process. However there really is a severe drought of qualified developers with clearance, to the degree that even the worthless ones don't really get fired if they show up and don't anger security. And while for some of the jobs that may indeed be a hard requirement, for most of them its more of a preference. If you are a good programmer and fairly confident you will be able to be cleared, then they will sponsor you through the clearance process. Pro-tip just don't lie about shit and should be able to get clearance, they will look over most past issues if you acknowledge them and state that they are no longer an issue.