This basic Recommendation presents guidance on the management of physical security concerned with electromagnetic interference and/or emanation@ for telecommunications centre managers to implement the information security management system (ISMS) requirements of Recommendation [ITU-T X.1051]. The relationship between [ITU-T X.1051] and this Recommendation is shown as Figure 1. There are two primary categories on the electromagnetic security. One is high-power electromagnetic interference@ either natural (such as lightning) or deliberate (malicious EM attack) that causes damage and disruption for telecommunication centre equipment such as switching@ transmission@ radio and power. Another is information leakage from unintentional emanations of telecommunication equipment such as servers@ computers and transmission equipment@ which process or carry information. There is the possibility that a malicious and sophisticated eavesdropper could reconstruct significant information from intercepted emanations. This Recommendation is a guide for the application of [ITU-T K.78] (HEMP)@ [ITU-T K.81] (HPEM)@ [ITU-T K.84] (information leakage) [ITU-T K.115] (mitigation method) and K series Recommendations on lightning protection. This Recommendation represents an overview of electromagnetic security; it classifies the environments where devices and equipment in need of protection are installed@ and classifies predicted threats and vulnerabilities as well as countermeasures.