I disagree with you on this, Joseph. The US Department of the Interior "protects America’s natural resources and heritage, honors our cultures and tribal communities, and supplies the energy to power our future" (
http://www.doi.gov/index.cfm ). This is not at all what the Argentine Ministerio del Interior is responsible for: "Es competencia específica del Ministerio del Interior y Transporte, asistir al Presidente de la Nación, y al Jefe de Gabinete de Ministros, en orden a sus competencias, todo lo inherente al gobierno político interno y al ejercicio pleno de los principios y garantías constitucionales, asegurando y preservando el régimen republicano, representativo y federal, así como en todo lo concerniente al Transporte."
http://www.mininterior.gov.ar/ministerio/ministerio.php?idNa...
In my opinion, when translating this kind of term it is better to use a generic term (in this case Ministry of the Interior or Interior Ministry, with Ministry of Home Affairs as an alternative possibility). If the translation were for the UK, I would not translate it as "Home Office".