## 5 Challenges and Future Directions
### Regulations and Security  
Despite the rapid growth of UAVs, there is an urgent need for regulatory bodies to develop standardized regulations for operating drones across different countries. A major obstacle to broader UAV adoption is the ambiguity or lack of clear standards and regulations around permitted airspace, size, height limits, privacy considerations, cost, safety requirements, and operating characteristics. In addition, there is a lack of consistency in government rules for UAV deployment. UAVs can impact commercial airplane navigation; therefore, countries should implement proper regulations and procedures for drone operations. For example, in the US, the Federal Aviation Administration (FAA) issued certificates and air traffic rules for UAV operations [220]. The regulatory and policy frameworks surrounding UAV operations in urban areas pose technical challenges. The lack of complete and operational regulatory frameworks and traffic management infrastructure hinders the widespread use of UAVs in an urban airspace [219].  
Addressing these challenges requires the development of comprehensive regulations and standards that ensure the safe and efficient operation of UAVs in urban environments. Additionally, policy frameworks need to be designed to support the integration of UAVs into the climate change research and mitigation strategies in cities. AI algorithms for regulatory compliance can provide a viable approach to support risk mitigation, improved confidential data security, and rapid adaptation to new regulations. With AI-enabled systems, UAVs can achieve authorization for domestic use across various countries by ensuring they meet the specific operational rules of each geographic location. By incorporating AI for standardized compliance, drones can be rapidly deployed in many nations while satisfying each region's regulations for risk, data privacy, and flight requirements. AI can potentially allow UAVs to comply with disparate regulations across borders efficiently. Ensuring the security of sensitive UAV data, such as position and location, presents a critical challenge. Since UAVs lack encryption, there is a risk of hijacking. Hacking and cyber liability are key concerns for UAV use. In military operations, UAVs face the potential threats of data leakage. Hackers can gain complete UAV control to steal data or invade privacy and illegal activities, such as smuggling. The lack of encryption leaves drones vulnerable to hijacking, hacking, and data theft. This poses significant security risks, especially for military UAVs where sensitive information can be leaked. Protecting position, navigation, and other critical data are urgent priorities to prevent hackers from commandeering UAVs for illegal purposes, such as privacy invasion and smuggling.  
Another concern regarding using UAVs, especially in cities, is privacy. UAV cameras and equipment that can take photographs or record videos raise significant privacy and security concerns, potentially violating individual rights [221]. In the USA, the Center for Democracy and Technology (CDT) advised the Federal Aviation Administration (FAA) to develop regulations explicitly preserving privacy. Privacy by Design (PbD) was introduced to address this challenge, supporting remedies for privacy breaches [222]. PbD regulations notably restrict intrusive UAV monitoring. Additionally, consistent UAV flights over companies can damage their market value by exposing their trade secrets and strategic plans. Drones equipped with cameras and sensors pose risks of infringing on privacy rights and commercial secrets through persistent surveillance.