A diplomat from the European Union Delegation in a third country must coordinate a joint crisis operation with a team of experts from the European Commission and local authorities. The team needs to share large volumes of confidential documents, collaborate in real time, and access data analysis applications from mobile devices on an insecure public network. Based on the principles of digital security and the functions of the European External Action Service (EEAS) to ensure the coherence and coordination of international action, what is the most robust security strategy aligned with EU standards to manage this scenario?