In an information security management system (ISMS), based on Recommendation
ITU-T X.1051 and ISO/IEC Standards 27001 and 27002, physical security is a key issue. The electromagnetic interference caused by a high-power electromagnetic (HPEM) attack and the ability to intercept information due to unintentional electromagnetic emissions of equipment are significantly determined by the applied physical security measures.

When security is managed, it is necessary to evaluate the threat and mitigate either the equipment or the site. The threat is related to "vulnerability" and "confidentiality" in ISMS.

Recommendation ITU-T K.81 presents guidance on establishing the threat level presented by an intentional HPEM attack and the physical security measures that may be used to minimize this. The HPEM sources considered are those presented in IEC 61000-2-13, High-power electromagnetic (HPEM) environments  Radiated and conducted, as well as some additional sources that have emerged more recently.

This Recommendation also gives vulnerability of equipment. The equipment is assumed to meet the immunity requirements presented in Recommendation ITU-T K.48 and relevant resistibility requirements, such as Recommendations ITU-T K.20, ITU-T K.21 and ITU-T K.45.