Defence context for the UK's Defence Engagement (Health).

Defence Engagement (DE) has been a core UK Defence task since 2015. DE (Health) is the use of military medical capabilities to achieve DE effects within the health sector to achieve security and defence objectives. DE (Health) practitioners must understand the underlying defence context that shapes these objectives. The strategic context is becoming more uncertain with the return of great power competition layered on enduring threats from non-state actors and transnational challenges. The UK response has been to develop the Integrated Review, outlining four national security and international policy objectives. UK Defence has responded by developing the integrated operating concept, differentiating military activity between operating and warfighting. Engage is one of the three functions of operate activity, which is complementary to the other operate functions of protect and constrain. DE (Health) can play a unique role in engagement, given its ability to develop new partnerships through health-related activity. DE (Health) may be an enabler for other engagements or to enable the protect and constrain functions. This will be dependent on delivering improvement in health outcomes. Therefore, the DE (Health) practitioner must be conversant with both the contemporary defence and global health contexts to deliver effective DE (Health) activities. This is an article commissioned for the DE special issue of BMJ Military Health.