An EU Commission official is preparing a confidential report on a new EU foreign policy mission in a conflict region. The report contains sensitive personal data of informants and requires real-time collaboration with delegations in third countries. The official must choose a technological solution that ensures the security of the data, complies with the General Data Protection Regulation (GDPR) and allows for effective coordination with international missions. Considering the role of the European External Action Service (EEAS) and the EU's digital security principles, what is the most appropriate strategy to manage this scenario?