The National Counter Terrorism Security Office (NaCTSO) is a police unit. It is funded by, and reports to, the Home Office, which advises the British government on its counter-terrorism strategy. The National Counter Terrorism Security Office supports the protection of the United Kingdom's crowded spaces, hazardous and potentially vulnerable or at risk sites, as well as offering advice on a range of threats and dangerous substances. They work alongside the Centre for the Protection of National Infrastructure.