The infliction of war and military aggression upon children must be considered a violation of their basic human rights and can have a persistent impact on their physical and mental health and well-being, with long-term consequences for their development. Given the recent events in Ukraine with millions on the flight, this scoping policy editorial aims to help guide mental health support for young victims of war through an overview of the direct and indirect burden of war on child mental health. We highlight multilevel, need-oriented, and trauma-informed approaches to regaining and sustaining outer and inner security after exposure to the trauma of war. The impact of war on children is tremendous and pervasive, with multiple implications, including immediate stress-responses, increased risk for specific mental disorders, distress from forced separation from parents, and fear for personal and family's safety. Thus, the experiences that children have to endure during and as consequence of war are in harsh contrast to their developmental needs and their right to grow up in a physically and emotionally safe and predictable environment. Mental health and psychosocial interventions for war-affected children should be multileveled, specifically targeted towards the child's needs, trauma-informed, and strength-and resilience-oriented. Immediate supportive interventions should focus on providing basic physical and emotional resources and care to children to help them regain both external safety and inner security. Screening and assessment of the child's mental health burden and resources are indicated to inform targeted interventions. A growing body of research demonstrates the efficacy and effectiveness of evidence-based interventions, from lower-threshold and short-term group-based interventions to individualized evidence-based psychotherapy. Obviously, supporting children also entails enabling and supporting parents in the care for their children, as well as providing post-migration infrastructures and social environments that foster mental health. Health systems in Europe should undertake a concerted effort to meet the increased mental health needs of refugee children directly exposed and traumatized by the recent war in Ukraine as well as to those indirectly affected by these events. The current crisis necessitates political action and collective engagement, together with guidelines by mental health professionals on how to reduce harm in children either directly or indirectly exposed to war and its consequences.