Modern cities face rapid growth and increasing complexities that demand innovative approaches for infrastructure management and urban security. Passive defense has emerged as a critical strategy to mitigate vulnerabilities and enhance urban resilience. In this context, the Internet of Things (IoT) presents advanced tools and capabilities to manage urban crises and threats effectively. Urban planners play a pivotal role in this process by designing resilient infrastructures capable of leveraging IoT technologies while minimizing associated risks.The IoT connects and coordinates various devices and systems, offering unparalleled potential to improve urban functionality. Its application in passive defense can significantly bolster urban crisis management and performance. Given the dynamic nature of urban environments, urban planners must adopt IoT-driven strategies to strengthen passive defense. By integrating smart IoT-based systems, planners can enhance resilience, reduce vulnerabilities, and improve urban security and sustainability. This integration encompasses the design of robust infrastructures, the implementation of monitoring systems, and the prediction of emergency scenarios, thereby advancing urban security and sustainability (Tang et al. ,2024) Moreover, as cities expand, the interconnected nature of urban infrastructure becomes more complex, increasing the potential for cascading failures during crises. Passive defense strategies supported by IoT technologies can help break these chains of vulnerability, allowing for better-prepared and adaptive urban environments.
Methodology
In terms of nature, the present research method is considered as mixed research (quantitative-qualitative) and in terms of purpose, it is considered as applied research.The present research approach is quantitative and qualitative. First, by using MAXQDA analytical software, secondary, central and selective codes were extracted to identify the factors affecting the role of urban planners in the design of smart urban systems using the Internet of Things to strengthen non-agent defense.The statistical population of the current research included specialists and experts in the field of urban planning and urban planning, including university professors, urban planning consultants, doctoral students in urban planning and urban planning, experts and municipal managers, etc.Sampling was selective and by snowball sampling method. The sample size was 40 people until scientific saturation. Document analysis is a systematic process of reviewing and evaluating documents (both printed and electronic).In this research, the descriptive level included qualitative and quantitative data descriptions. Regarding the qualitative data, the descriptions were derived from retelling and quoting the texts and final writings. In addition, the descriptive level of the analysis included the description of the main features of the data, summarizing the methodology, logic of the analysis and the results of the articles, books, plans, etc.
Results and discussion
The IoT empowers urban planners to improve resilience and reduce vulnerabilities to diverse crises and threats. By providing real-time and accurate data on urban conditions, the IoT facilitates crisis prediction and management, significantly enhancing urban security and functionality (Gkontzis et al., 2024). However, the successful integration of IoT in urban systems requires addressing several critical aspects, including:
1. Infrastructure Design: Smart city planning necessitates the development of robust, adaptive infrastructures that can integrate IoT technologies while withstanding environmental and human-made challenges.
2. Data Management: Effective utilization of IoT relies on accurate data collection, storage, and analysis. Urban planners must ensure that data systems are secure and accessible to facilitate informed decision-making.
3. Cybersecurity: As IoT devices are interconnected, they are susceptible to cyber threats. Robust cybersecurity measures are crucial to protect sensitive data and ensure the reliability of IoT systems.
4. Policy and Regulation: Governments and local authorities must establish policies and regulations to guide IoT implementation in urban planning, ensuring compliance with ethical, legal, and safety standards.
5. Collaboration and Training: Successful IoT integration requires collaboration among stakeholders, including urban planners, technologists, and policymakers. Training programs for urban planners are essential to build expertise in IoT-based systems.
Singapore's example highlights the effectiveness of IoT in passive defense. The city's smart systems include real-time monitoring, predictive analytics, and automated response mechanisms, which have significantly improved urban resilience and security. Urban planners in Singapore have utilized IoT technologies to create interconnected systems that address various urban challenges, from traffic management to disaster preparedness.
Additionally, Singapore's approach demonstrates the importance of integrating citizen engagement in IoT-based urban systems. By involving the public in the planning process and providing access to smart city technologies, urban resilience can be further enhanced. Such practices foster trust and cooperation between citizens and authorities, ensuring a collective effort in managing urban risks.
The review of the research findings shows that by reviewing the specialized research literature, various things were identified, including adaptability, transparency, flexibility, realism, decentralized and participatory planning.
(Optimization of resources and infrastructure using the Internet of Things in the field of water, energy and traffic---Predicting and managing crises with the Internet of Things in the field of earthquakes, floods and air pollution-- Improving urban security and resilience with the Internet of Things in the field of monitoring and response to threats),
Realism, communication and coordination affect the realization of non-agent defense using artificial intelligence and Internet of Things with the role of urban planners. Finally, according to Yindi's rating of realism or 49., decentralized and participatory planning with 54., communication and systematization with 43. and flexibility 4. are among the most important items to strengthen non-agent defense.

Conclusion
The findings indicate that IoT plays a vital role in enhancing passive defense by offering advanced tools for resource management, crisis prediction, and urban security improvement. However, successful IoT implementation requires addressing technical, economic, and social challenges. Urban planners must design smart and efficient infrastructures while considering these challenges to maximize IOT capabilities. This study demonstrates how urban planners can utilize IoT technologies to improve urban resilience and security. IoT has revolutionized crisis management and threat mitigation by providing innovative tools and systems. However, its effective application demands careful planning, technical expertise, and collaboration among stakeholders. Urban planners have a unique opportunity to create cities that are not only smarter but also safer and more resilient. By addressing cybersecurity concerns, optimizing resource management, and ensuring inclusive policies, they can leverage the transformative potential of IoT technologies.