An EMP-protective composite structure that includes at least one enclosure having walls, a ceiling, at least one ingress/egress portal and a base, each of the walls, the ceiling, the ingress/egress portal and the base including at least one blast-resistant structural panel and at least one layer of an EMP barrier that provides magnetic conduction, field absorption and field reflection fully-enclosing the structural panel. An encapsulation barrier is provided having a blast-deflecting surface overlying the at least one enclosure. A HEMP door or circuitous path is provided from an exterior of the EMP-protective structure, through the encapsulation barrier and to the at least one ingress/egress portal of the enclosure. The circuitous path is configured to absorb and deflect EMP as the EMP passes along the circuitous path. Embodiments of the blast-resistant structural panel are also disclosed.