The UPDATE project will serve to define requirements, architecture and a development plan for a Minimum Viable Product (MVP) of a UK National PNT Digital Twin Environment (DTE). The MVP will meet the immediate needs of the UK Government with respect to delivery of its Policy Framework for Greater PNT Resilience (10-point plan). It will provide data in support of the development of business cases and inform critical decision making in the run-up to the next governmental spending review. The proposed scope will allow government planners to better understand the immediate risk to the UK resulting from the use of PNT, the loss of PNT and the impact of certain options to strengthen and improve the UK’s resilience to those risks. The DTE will be designed to be modular, flexible and extendible to adapt to the modelling and analysis needs of the UK PNT Office as they assess options, evaluate alternatives and scrutinise investment cases concerning future PNT systems, services, applications and regulations. The DTE will provide quantitative data to support planning for the future and decision making where it supports and informs operational resilience and system deployments.