When the Secret Service prostitution scandal broke in Cartagena, Colombia, the problem wasn't so much that the Secret Service agents were paying for sex, but rather that the prostitutes may have been spies. Now, Sen. Chuck Grassley, R-Iowa, is saying that the prostitutes could have been Russian spies.

Twelve Secret Service agents and various members of the military were assigned to do advance security for President Barack Obama's trip to Colombia, but were later embroiled in a scandal after bringing back as many as 21 prostitutions to their rooms in up to two different hotels.

The issue here isn't just people messing around with prostitutes, Grassley told reporters in Iowa, according to Roll Call. The issue is the security of the president of the United States and the issue is any national security implications that it might have because of the secrecy and the documents and things of that nature.

Grassley clarified that he had no specific information leading him to believe that the women were Russian spies.

A few of the Secret Service agents were married, which left them open to blackmail attempts by those who may have known that they were with prostitutes.

Though Grassley's claim seems a bit extraordinary nowadays, prostitutes as spies were a very real threat in earlier times.

During World War I, for example, Dutch exotic dancer Mata Hari, born Margaretha Geertruida Zelle, was executed by firing squad in France after being charged with spying for Germany. She was eventually arrested in her hotel room in Paris's Hotel Plaza Athénée and put on trial for spying for Germany, and the prosecution even claimed she was responsible for the deaths of at least 50,000 soldiers.

She denied the accusations, writing that My international connections are due to my work as a dancer, nothing else. [...] Because I really did not spy, it is terrible that I cannot defend myself. In the 1970s, however, documents unsealed in Germany revealed that she truly was a spy, and had entered the service in 1915 during a trip to Köln, Germany.

The Cold War was also filled with prostituted-related espionage. Bucharest's Athénée Palace, for example, was filled with prostitute-spies working for the Romanian secret service, the Securitate. According to a Dan Halpern, [t]he prostitutes in the lobby and in the bar and in the nightclub reported directly to their employers.

Israel's Mossad also used prostitutes as tools of espionage. Shulamit Cohen, for example, worked as a prostitute in Beirut from 1947 until 1961, servicing many high-level government officials and reporting back to her handlers in Israel.