An EU Commission team, using cloud computing tools managed by external providers (SaaS) and generative AI platforms to analyze large volumes of EU citizens' data, plans to implement a new data processing system that involves the transfer of personal information to a third country. The team must ensure rigorous compliance with the General Data Protection Regulation (GDPR) and cybersecurity principles. Which of the following technical and organizational measures is the MOST critical and specific to guaranteeing the protection of personal data during this international transfer and use of AI, based strictly on the principles of GDPR and EU digital security best practices?