As a Project Manager how would you handle uncertainty in a globally distributed project?

Imagine you are an IT Project Manager for a globally distributed IT project. You have a cross-functional team with members across multiple countries and time zones.

Due to a geopolitical situation, some team members who were responsible for critical components are suddenly unreachable and you can no longer establish any communication.

Have you ever been in similar situation?

During this uncertainty, what are the most important things to do and how would you ensure business continuity?