MI5 (Military Intelligence, Section 5), [2] officially the Security Service, is the United Kingdom's domestic counter-intelligence and security agency and is part of its intelligence machinery alongside the Secret Intelligence Service (MI6), Government Communications Headquarters (GCHQ), and Defence Intelligence (DI).

Discover how MI5 works to protect against threats to national security through intelligence gathering techniques, partnerships and legislation. Find out how you can play your part in keeping the...

Jan 15, 2025 · MI5, intelligence agency charged with internal security and domestic counterintelligence activities of the United Kingdom. It is authorized to investigate any person or movement that might threaten the country’s security.

MI5 exists to protect the UK from threats to our national security, primarily terrorism and threats posed by states. More than 5,000 people work at MI5, bringing together people with lots of...

MI5 protects the UK against threats to national security. Threats can range from terrorism to attempts by states to harm people in the UK and undermine our way of life. We carry out...

The Security Service, commonly known as MI5, is one of three British intelligence agencies. It is the security agency responsible for counter-intelligence inside the United Kingdom. It gives the government information about hostile activities inside the UK.

Although the “MI” stands for “Military Intelligence”, MI5 is a civilian agency without formal executive powers. MI5 is principally concerned with countering threats to domestic security – in contrast to MI6, which is concerned with external security.

The Security Service, MI5, is responsible for protecting the UK against threats to national security. MI5 works with the Home Office is supported by 1 public body.