MI5 in the context of "FBI"

The Federal Bureau of Investigation (FBI) is the primary federal law enforcement agency in the United States and also the American domestic intelligence and security service. An agency of the United States Department of Justice, the FBI is a member of the U.S. Intelligence Community and reports to both the attorney general and the director of national intelligence. A leading American counterterrorism, counterintelligence, and criminal investigative organization, the FBI has jurisdiction over violations of more than 200 categories of federal crimes. The FBI maintains a list of its top 10 most wanted fugitives.

Although many of the FBI's functions are unique, its activities in support of national security are comparable to those of the British MI5 and NCA and the Russian FSB. Unlike the Central Intelligence Agency (CIA), which has no law enforcement authority and is focused on intelligence collection abroad, the FBI is primarily a domestic agency, maintaining 56 field offices in major cities throughout the United States, and more than 400 resident agencies in smaller cities and areas across the nation. At an FBI field office, a senior-level FBI officer concurrently serves as the representative of the director of national intelligence.

Cromwell Road is a major London road in the Royal Borough of Kensington and Chelsea, designated as part of the A4. It was created in the 19th century and is said to be named after Richard Cromwell, son of Oliver Cromwell, who once owned a house there.

The Security Service (MI5) was based at 35 Cromwell Road from 1929 to 1934.

Counterintelligence (counter-intelligence) or counterespionage (counter-espionage) is any activity aimed at protecting an agency's intelligence program from an opposition's intelligence service. It includes gathering information and conducting activities to prevent espionage, sabotage, assassinations or other intelligence activities conducted by, for, or on behalf of foreign powers, organizations or persons.

Many countries will have multiple organizations focusing on a different aspect of counterintelligence, such as domestic, international, and counter-terrorism. Some states will formalize it as part of the police structure, such as the United States' Federal Bureau of Investigation (FBI). Others will establish independent bodies, such as the United Kingdom's MI5, others have both intelligence and counterintelligence grouped under the same agency, like the Canadian Security Intelligence Service (CSIS).

A security agency is a governmental organization that conducts intelligence activities for the internal security of a state. They are the domestic cousins of foreign intelligence agencies, and typically conduct counterintelligence to thwart other countries' foreign intelligence efforts.

For example, the United States Federal Bureau of Investigation (FBI) is an internal intelligence, security and law enforcement agency, while the Central Intelligence Agency (CIA) is an external intelligence service, which deals primarily with intelligence collection overseas. A similar relationship exists in Britain between MI5 and MI6.

The Government of the United Kingdom maintains several intelligence agencies that deal with secret intelligence. These agencies are responsible for collecting, analysing and exploiting foreign and domestic intelligence, providing military intelligence, performing espionage and counter-espionage. Their intelligence assessments contribute to the conduct of the foreign relations of the United Kingdom, maintaining the national security of the United Kingdom, military planning, public safety, and law enforcement in the United Kingdom. The four main agencies are the Secret Intelligence Service (SIS or MI6), the Security Service (MI5), the Government Communications Headquarters (GCHQ) and Defence Intelligence (DI). The agencies are organised under three government departments, the Foreign Office, the Home Office and the Ministry of Defence.

Although the history of the organisations dates back to the 19th century or earlier, the British intelligence system as we know it today – with components for domestic, foreign, military, and communications intelligence – did not emerge until the years immediately preceding World War I. The decryption of the Zimmermann Telegram in 1917 was described as the most significant intelligence triumph for Britain during World War I, and one of the earliest occasions on which a piece of signals intelligence influenced world events. During the Second World War and afterwards, many observers regarded Ultra signals intelligence as immensely valuable to the Allies of World War II. In 1962, during the Cuban Missile Crisis, GCHQ interceptions of Soviet ship positions were sent directly to the White House. Intelligence cooperation in the post-war period between the United Kingdom and the United States became the cornerstone of Western intelligence gathering and the "Special Relationship" between the United Kingdom and the United States.

Nancy Clara Cunard (10 March 1896 – 17 March 1965) was a British writer, heiress and political activist. She was born into the British upper class, and devoted much of her life to fighting racism and fascism. She became a muse to some of the 20th century's most distinguished writers and artists, including Wyndham Lewis, Aldous Huxley, Tristan Tzara, Ezra Pound and Louis Aragon—who were among her lovers—as well as Ernest Hemingway, James Joyce, Constantin Brâncuși, Langston Hughes, Man Ray and William Carlos Williams. MI5 documents reveal that she was involved with Indian diplomat, orator, and statesman V. K. Krishna Menon.

In later years she suffered from mental illness, and her physical health deteriorated. When she died in the Hôpital Cochin, Paris, she weighed only 26 kilograms (57 pounds; 4 stone 1 pound).

The Home Office (HO), also known (especially in official papers and when referred to in Parliament) as the Home Department, is the United Kingdom's interior ministry. It is responsible for public safety and policing, border security, immigration, passports, and civil registration.

Agencies under its purview include police in England and Wales, Border Force, the Visas and Immigration authority, and the Security Service (MI5). It also manages policy on drugs, counterterrorism, and immigration. It was formerly responsible for His Majesty's Prison Service and the National Probation Service, but these have been transferred to the Ministry of Justice.

Defence Intelligence (DI) is an organisation within the United Kingdom intelligence community which focuses on gathering and analysing military intelligence. It differs from the UK's intelligence agencies (MI6, GCHQ and MI5) in that it is an integral part of a government department – the Ministry of Defence (MoD) – rather than a stand-alone organisation. The organisation employs a mixture of civilian and military staff and is funded within the UK's defence budget. The organisation was formerly known as the Defence Intelligence Staff (DIS), but changed its name in 2009.

The primary role of Defence Intelligence is that of 'all-source' intelligence analysis. This discipline draws information from a variety of overt and covert sources to provide the intelligence needed to support military operations, contingency planning, and to inform defence policy and procurement decisions. The maintenance of the ability to give timely strategic warning of politico-military and scientific and technical developments with the potential to affect UK interests is a vital part of the process.