Good article, and shows the vulnerability of GPS to simplistic devices. eLoran was proposed as a ground-based backup to GPS for situations such as this, as jamm

Good article, and shows the vulnerability of GPS to simplistic devices. eLoran was proposed as a ground-based backup to GPS for situations such as this, as jamming that signal would take resources your ordinary consumer wouldn't have. However, the funding for this was nixed and most/all of the towers were torn down.