Russia's horrific war against Ukraine has radically changed international security. NATO will need to continue bolstering its Deterrence and Defence Posture, which is essential to ensuring the collective defense of Allies and to continue investing in crisis management and cooperative security while adapting these tasks to meet its changing security needs and globally integrated hybrid environment. The Alliance should pay a strong emphasis on retaining and strengthening technological edge, in particular, improving strategic forecasting and situational awareness, the ability to understanding, monitoring and prediction the actions of potential adversaries using means of intelligence, surveillance and reconnaissance based on comprehensive agreements in this sphere. The purpose of the study is to analyze the development, improvement and application experience of NATO's Joint Intelligence, Surveillance and Reconnaissance (JISR) as a priority area of the Alliance's transformation in terms of improving capabilities, as well as the significance for future operations and the decision-making process There were determined definitions, content, main components and means of the system of NATO's Joint Intelligence, Surveillance and Reconnaissance. Conceptual and doctrinal documents for the implementation of NATO's obligations in this area have been studied. The security conditions, the process of formation based on experience and best practices, vulnerabilities and key areas of the system, which combines the potential of intelligence, surveillance and reconnaissance based on phased approach were analysed. There were considered the projects that provide gather of data and information, which JISR brings together, such as NATO’s Alliance Ground Surveillance (AGS) system, NATO Airborne Warning & Control System (AWACS) surveillance aircraft and national JISR assets from the space, air, land and maritime domains/ Highlighted are the key aspects of the process of interpretation and analysis of information, requirements for the professional level of experts and the importance of the final product for the decision-making process. There were indicated further development and improvement of JISR capabilities in training and education, doctrine and procedures and networking environment spheres. Considered are methods to practice and evaluate technical and operational concepts for conducting NATO`s Joint Intelligence, Surveillance and Reconnaissance. An overview of the possibilities of applying Ukrainian innovative developments tested in combat conditions in terms of situational awareness as well as Ukraine's cooperation with NATO in this field was made. The result of the research is conclusions on the development and improvement of JISR capability to facilitate rapid decision-making in several main areas, including the Readiness Action Plan, enhanced Forward Presence, the hybrid warfare strategy, and the overall Deterrence and Defence Posture. Keywords: NATO, intelligence, surveillance, reconnaissance, situational awareness, NATO Ground Surveillance System, Airborne Early Warning and Control System, Deterrence and Defence Posture, enhanced Forward Presence, decision-making process, operation and mission.