Preface Purpose 1. Joint Doctrine Note (JDN) 1/18, Cyber and Electromagnetic Activities attempts to capture the widest concept of cyber and electromagnetic activities (CEMA) and draws together elements of existing doctrine and best practice. However, the principles and concepts expressed are not yet wholly agreed. This JDN sets a baseline for CEMA within UK Defence, Government Communications Headquarters (GCHQ) and other partners across government (PAG). It provides a working description of the CEMA environment and will enable the single Services to develop a tailored CEMA concept whilst remaining aligned with Joint Forces Command (JFC) and GCHQ intent. Context 2. To succeed against complex and diverse threats that exploit the pervasive information environment we need to do things differently. At the heart of this concept is the enhancement of joint action and, therefore, our influence by contesting the information environment, being more integrated as a force and more adaptable to changing circumstances. Conventional and non-conventional adversaries may be state or non-state; and may employ mission-tailored, decentralised, asymmetric and agile actors. Therefore, it is important that we have doctrine that examines how we adapt operations to the changing environment rather than trying to control it. This is the context within which Defence must undertake CEMA. 3. JDN 1/18, aims to clarify the nature of CEMA and offers guidance on how to enable, realise, employ and exploit it. It considers how CEMA supports understanding, offensive and defensive actions and how it enables commanders and staff to make effective decisions and create effects within the full spectrum approach. Audience 4. This publication is aimed at military commanders and staff (J1-J9) at Permanent Joint Headquarters and at higher tactical levels. It should also JDN 1/18 iii