The UK Government views the energy sector as a critical part of the economy. Despite the National Security and Investment Act 2021 (“NSIA”) only having been in full force for just over a year now (from January 2022), we have already seen the Investment Security Unit (ISU) taking a keen interest in energy deals across the sector. Below, we set out some key observations emerging from the interventions and guidance to date on how the NSIA is being applied to the energy sector.