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MI5 vs. MI6: What's the Difference?

Edited by Harlon Moss || By Janet White || Updated on November 6, 2023
MI5 is the UK's domestic counter-intelligence and security agency, while MI6, known officially as SIS, operates as the UK's foreign intelligence service.

Key Differences

MI5, formally titled the Security Service, focuses primarily on internal security in the UK, identifying and managing threats within the nation's borders. In contrast, MI6, the Secret Intelligence Service (SIS), works outside the UK to gather intelligence that pertains to the country's security.
MI5 operates with the main objective of protecting national security against threats like terrorism and espionage within the United Kingdom. Conversely, MI6 deals with the collection of foreign intelligence, often working covertly abroad to gather information.
While both MI5 and MI6 collaborate on matters of national security, their operational scopes differ significantly. MI5 works closely with law enforcement and other security agencies on home soil, whereas MI6 operates internationally, often in secrecy, coordinating with foreign intelligence services.
The jurisdiction of MI5 is limited to domestic affairs; it does not conduct operations outside of the UK but instead handles risks such as domestic terrorism, cyber threats, and counter-espionage. Alternatively, MI6 undertakes intelligence operations globally, focusing on issues that affect the UK's security but originate abroad.
The oversight and accountability for MI5 involve various bodies, including the Home Office and the Investigatory Powers Tribunal, ensuring its operations comply with domestic law. In contrast, MI6, while also subject to rigorous oversight mechanisms, works more independently overseas, often in environments where the UK's influence and legal jurisdiction are limited.

Comparison Chart

Official Title

Security Service
Secret Intelligence Service (SIS)

Operational Scope


Main Objectives

Counter-terrorism, counter-espionage
Collection of foreign intelligence


United Kingdom


Home Office, Investigatory Powers Tribunal
Foreign Office, Investigatory Powers Tribunal

MI5 and MI6 Definitions


"MI5 is the UK's domestic security agency."
The suspect was under MI5 surveillance for weeks.


"MI6 collects foreign intelligence."
MI6 provided crucial information that shaped the government's foreign policy.


"MI5 protects against internal threats."
MI5 thwarted a planned attack on a public event.


"MI6 works covertly abroad."
The MI6 agent was deep undercover in the hostile country.


"MI5 focuses on counter-terrorism."
MI5's efforts prevented the radical group's expansion.


"MI6 operates internationally."
The diplomat was actually an MI6 operative gathering intelligence.


"MI5 collaborates with UK law enforcement."
The police carried out the arrest with MI5's intelligence.


"MI6 operates with significant independence."
MI6 executed a sensitive operation without the host country's knowledge.


"MI5 operates under legal oversight."
MI5's operations were reviewed for strict compliance with human rights laws.


"MI6 focuses on global issues affecting the UK."
MI6 monitored foreign powers' activities that posed a potential threat.


What is MI6?

MI6, or the Secret Intelligence Service (SIS), is the UK's foreign intelligence service, operating internationally.

Where does MI6 operate?

MI6 operates outside the UK, globally, to gather intelligence beneficial to national security.

What is MI5?

MI5 is the UK's domestic security service, focusing on internal threats such as terrorism and espionage.

Where does MI5 operate?

MI5 operates within the United Kingdom, focusing on national security.

How is MI5 organized?

MI5 is organized into several branches, each responsible for different aspects of national security.

What does MI6 primarily do?

MI6 collects foreign intelligence, often covertly, to inform the UK's national security strategy.

How is MI6 structured?

MI6 also has various branches, each handling different regions or types of foreign intelligence.

Who oversees MI5's activities?

MI5 is overseen by the Home Office and judicial bodies like the Investigatory Powers Tribunal.

Does MI6 operate within the UK?

MI6 focuses on foreign intelligence; domestic operations are the remit of MI5.

Can MI5 operate overseas?

Generally, MI5 does not operate overseas; its jurisdiction is primarily domestic.

What are MI5's main responsibilities?

MI5's primary duties are counter-terrorism, counter-espionage, and domestic security.

Who can work for MI5?

UK citizens who pass rigorous background checks and meet specific criteria can work for MI5.

Do MI5 and MI6 collaborate?

Yes, they often collaborate when domestic and foreign security issues intersect.

Are MI5's activities made public?

Generally, MI5's operations are confidential, but some information may be released to the public retrospectively.

Is MI5 involved in political policing?

MI5's mandate is national security; it is not a law enforcement agency, nor does it handle regular criminal activities.

Are MI6's operations classified?

Most MI6 operations are highly classified, given the sensitive nature of foreign intelligence.

Who is in charge of overseeing MI6?

MI6 reports to the Foreign Office, with oversight from bodies like the Investigatory Powers Tribunal.

How do MI5 and MI6 differ in their operations?

MI5 deals with threats within the UK, while MI6 handles threats originating from abroad.

Who can be an MI6 agent?

Similar to MI5, potential MI6 agents must be UK citizens, pass strict background checks, and fulfill certain requirements.

Does MI6 engage in espionage?

Yes, espionage is a key part of MI6's work in collecting foreign intelligence.
About Author
Written by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.
Edited by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.

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