Internal Security Department (Singapore)

The Internal Security Department (ISD) is the domestic intelligence, counter-espionage and security agency of Singapore under the purview of the Ministry of Home Affairs (MHA). It is tasked to confront and address security threats ranging from subversion or sedition, spying or espionage, foreign influence, domestic or international terrorism, political or religious extremism, and fraud against the state.

Deputy Prime Minister Goh Keng Swee stated that the 'an efficient secret police' was necessary to counter dangers such as insurgencies and violent rebellions. The ISD is empowered to conduct mass surveillance and covert security operations; it has the utmost right to indefinitely detain without trial individuals suspected to be a threat to national security.

Although the agency falls under MHA, it is autonomous within the ministry. It is led by a director, who holds the rank equivalent to a permanent secretary, and reports directly to the Prime Minister's Office (PMO). The department is highly secretive; most of its personnel are only known to the country's top government officials.