No, for two reasons: as a government work, it is not subject to copyright protection, but also as such a short phrase (one letter!) it could only be protected as a trademark. Which it isn't.
Nobody. It's public domain.
No. Trademarks can be renewed, copyrights cannot.
A copyright pertains to ideas and purely intangible creations of the mind and is usually artistic in nature
Works of sufficient creativity are automatically protected by copyright as soon as they are fixed in a tangible medium.