The US had the intelligence to create the atomic bomb and the Soviet Union the spies to copy it. It was already a big difference. But the US had also the counterintelligence which was intended to decrypt messages transmitted by NKVD, the KGB and the GRU. This was the dominant task of the Venona Project which decrypted and translated more than 3000 messages. It was the proof of the existence of the Cambridge Five espionage ring in the United Kingdom and of course the Soviet espionage of the Manhattan Project in the United States. In fact it was a double victory for the US. The American scientists were the first and the best at that time. But the American code breakers were also the best. The code of the Soviet systems should be unique. But due to pressure, the Soviet code generators started duplicating cipher pages. This was a strategic error. With this the American code-breakers achieved to reconstruct the code used to convert text to numbers. Meredith Gardner and Marie Mayer were the Ventris and Chadwick of the cryptanalysis. They prove the existence of the Soviet espionage even in the Manhattan Project.