This paper reviews the strategic use of warning intelligence to pre-emptively address threats in complex geopolitical scenarios through rapid intelligence sharing. Specifically, the paper reviews the question How, based on research and experience, can a set of principles be applied by states to enhance situational awareness and tackle threat actors through a holistic and collaborative approach to intelligence sharing? The paper examines historical and contemporary alliances like the Five Eyes and reviews a Signals Intelligence Alliance as a case in point, highlighting the importance of collaborative approaches to enhance situational awareness and tackle threat actors. The study, grounded in the philosophical paradigm of interpretivism, adheres to the principles for transparent science when researchers use tools such as large-language-models as grammar editors or research assistants. The paper also acknowledges limitations such as the generalisability of the SIGINT model and the need for continuous adaptation of intelligence sharing practices. The results discuss policy, process, and people challenges to intelligence sharing. The paper concludes that successful intelligence sharing should follow eight general principles. Future research directions include exploring the impact of emerging technologies, human aspects of intelligence sharing, and context-based intelligence sharing alliances.