Special Relationship: Technology Sharing between the Intelligence Agencies of the United States and United Kingdom

Special Relationship: Technology Sharing Between the Intelligence Agencies of the United States and United Kingdom


During World War II, the intelligence services of the United States and the United Kingdom worked together in their efforts against the Axis powers, particularly in Europe, and formalized the collaboration with agreements in 1943 and 1946. Only in the postwar era did the United States emerge as the dominant partner, and even then, many of the most important technological advances in intelligence came from Britain. Among the most visible examples of U.S.-British cooperation in the early twenty-first century were joint military efforts in Afghanistan and Iraq. Behind these undertakings lay a more extensive framework of cooperation in intelligence, whose most significant known component is the Echelon global surveillance system.

U.S. and British relations through 1945. Great Britain is one of the only nations, other than Germany, against which Americans have fought twice: first in the Revolutionary War (1775–83), and later in the War of 1812. A century later, the two nations allied against the Central Powers in World War I. The "special relationship" between the Anglo-American powers only became apparent in World War II, when Italy and Russia signed pacts with the Nazis, and France readily capitulated to them. With Britain the only European nation opposing Hitler, the United States—which did not enter the war until two years after it began in Europe—transferred considerable war materiel to the United Kingdom through the Lend-Lease program.

At that time, Britain, with its vast empire, was still perceived as the greater of the two powers, and in many regards, it maintained the lead. Despite the legendary status that wartime U.S. intelligence efforts have gained in retrospect, it was the British who scored the single greatest intelligence breakthrough of the war: Ultra, the successful effort to decipher German radio transmissions made with the Enigma machine. This in turn gave the Allies an enormous advantage over the Germans, who only learned—along with the rest of the world—about Ultra long after the war was over.

Certainly the Soviets did not know about Ultra, or any number of other secrets maintained by the democratic portion of the allied force. In a stroke of good fortune for the postwar world, the instincts of the anticommunist British prime minister, Winston Churchill, prevailed over the desire of U.S. president Franklin D. Roosevelt to share information equitably, and the two countries withheld the most sensitive information from the Soviets. Dictator Josef Stalin did not even known about plans for the Normandy invasion almost until the launch of the attack in June 1944.

Formal agreements and technology-sharing. Midway of the war, the United States and United Kingdom formalized their special relationship with the British-United States Agreement (Brusa) of May 17, 1943. Brusa put into writing what had already existed in fact: virtually complete sharing of signals intelligence. As members of the British Empire, Australia and Canada—which also participated in the Normandy invasion—later also signed on to the agreement.

These four nations, along with New Zealand, became parties to the United Kingdom-United States of America Security Agreement, known as UKUSA, signed on March 5, 1946. UKUSA greatly extended the provisions of Brusa, allowing for standardized terminology, techniques, and procedures. After 1947, the U.S. National Security Agency took the lead in UKUSA, around which grew the vast intelligence-gathering network known as Echelon. Only in the late 1990s did Echelon become public knowledge.

Throughout much of the period before and during World War II, and for several decades thereafter, Great Britain played a powerful role in the technological dimension of this arrangement. The British had, if not the lead, at least a position of parity with the Americans where technological advances were concerned. Particularly notable were the many advances they made in the technology of naval warfare, both for aircraft carriers and the planes associated with them. One outstanding example of this is the British Harrier jet, whose unusual ability to hover made it an ideal craft for the U.S. Marines.

America's closest friend. In the years since Vietnam, as anti-Americanism took hold in much of western Europe and the developing world, Britain distinguished itself by its virtually unfailing support for the United States. This became particularly apparent following the September 11, 2001, terrorist attacks on the United States. The United Kingdom made this support concrete, first in the war against the Taliban regime in Afghanistan, and later against Saddam Hussein's dictatorship in Iraq. (Australia, too, supported the United States with troops in both efforts, while Canada provided troops for the Afghanistan war.) At the same time, British technological advances remained a vital aspect of the partnership: in October 2002, for instance, the U.S. General Services Administration awarded a contract to British software developer Autonomy for a system to used in tracking suspected terrorists.


Aldrich, Richard J. Intelligence and the War against Japan: Britain, America, and the Politics of Secret Service. New York: Cambridge University Press, 2000.

——. The Hidden Hand: Britain, America, and Cold War Secret Intelligence. Woodstock, NY: Overlook Press, 2002.

Richelson, Jeffrey. The Ties that Bind: Intelligence Cooperation between the UKUSA Countries. Boston: Unwin Hyman, 1990.

Whiting, Charles. The Spymasters: The True Story of Anglo-American Intelligence Operations within Nazi Germany, 1939–1945. New York: Saturday Review Press, 1976.


Chapman, Gary. "U.S.-British Cyber-Spy System Puts European Countries on Edge." Los Angeles Times. (August 16, 1999): 3.

Markoff, John. "British Concern to Help U.S. Track Terrorists." New York Times. (October 12, 2002): A8.


Aircraft Carrier
Enduring Freedom, Operation
Iraqi Freedom, Operation (2003 War Against Iraq)
United Kingdom, Intelligence and Security

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