Recent studies on the vulnerability of GPS to interference recommend that a backup system be made available to determine own-aircraft position for both navigation and surveillance services in the National Airspace System (NAS). This backup will provide horizontal-only position information during brief, localized GPS outages caused by system, natural or intentional-interference factors. MITRE performed an evaluation of the potential candidates for such a backup system.[1] The results of this analysis showed that enhanced LORAN (eLORAN) is likely the best choice among the alternatives studied. This paper concentrates first on three interference scenarios that have been postulated by MITRE, with which an adversary could attempt to intentionally interfere with LORAN. The second part of paper provides a preliminary assessment of eLORAN coverage degradation under a simplified interference scenario.