The evolution of 5G and the development of 6G networks demand a strategic approach to security challenges. ISP5G+ aims to address these challenges comprehensively, and in particular to: i) develop solutions aimed at protecting the mobile networks against security threats at the physical level, possibly adopting innovative components such as smart surfaces; ii) integrate mechanisms for safeguarding the network infrastructure as a whole, especially in emerging scenarios such as decentralized and distributed ones; and iii) implement tools for monitoring and ensuring the security of mobile networks in general, which, due to the heterogeneity of the involved applications, services, and devices, require specific and targeted approaches. Focusing on 5G security aspects, these ambitious objectives will effectively complement the research endeavors of the PE SERICS project.