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Document vault reveals FBI spied on Switzerland

FBI Director J. Edgar Hoover personally knew of the spy operation against Switzerland US Library of Congress

Newly unearthed documents from the Second World War era show that the American Federal Bureau of Investigation (FBI) was spying on Swiss diplomats during and after the war, even managing to break Swiss code to find out about Nazi gold and other secret affairs.

Under the United States’ Freedom of Information Act, the SonntagsZeitung and Le Matin Dimanche newspapers recently gained access to previously confidential files from the FBI – which reveal that the agency spied on diplomats from numerous countries, including Switzerland, during and immediately after the Second World War.

As of today, the documents are publically available on the website, a reference to the secret room in FBI headquarters where the many tons of secret files on other countries were kept. Then-FBI Director Herbert Hoover ordered them hidden there in 1948 to escape scrutiny by the US Congress, which was not informed of the spying project. Eventually, the huge volume of files kept there even endangered the structural integrity of the building.

Broken code

A document from June 17, 1942, describes how FBI investigators were able to break the Swiss code through photographs of encoded diplomatic documents obtained from a “top secret source”. The code was then broken in an FBI lab at the US Justice Department in Washington, D.C. The Americans were able to read Swiss code until at least 1950, when the code written with the Enigma encoding machine was replaced by code written with a Swiss-invented machine known as “Nema”.

The broken code helped FBI officials find the route of a Swiss High Seas Fleet, and Hoover distributed the code throughout the Special Intelligence Service so that further Swiss cables might be intercepted.

The bureau is also believed to have opened Swiss diplomatic letters, a practice illegal under international law. This is likely how the FBI found out that International Committee of the Red Cross delegate Jean de Wattewille used the Swiss diplomatic mail service illegally to smuggle private letters from third parties to addresses in Europe. De Wattewille was later interrogated in New York and an acquaintance of his was convicted of spying by the United States.

Nazi gold

After the war, the FBI was able to use the broken Swiss code to intercept and decipher documents revealing the amount Switzerland was willing to pay for Nazi gold hidden in Swiss banks.

When Swiss Minister Walter Stucki arrived in Washington for negotiations over the final amount in 1946, the Americans already knew the Swiss negotiating position and got them to pay the maximum amount of $250 million – an amount worth CHF1.3 billion today.

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SWI - a branch of Swiss Broadcasting Corporation SRG SSR