Spies in the Manhattan Project

Spies in the Manhattan project are accountable for why Russia was able to produce an atomic bomb so quickly--nearly 4 years after Hiroshima and Nagasaki.  Contrary to popular belief, there was no lack in recruits for spying, whether they were motivated by communist beliefs or nuclear parity (they thought that if no nation had a monopoly, a nuclear war would be prevented).  For many years, until the US and Britain deciphered the telegraph code, the governments did not know the extent of Soviet spying.  Here are three of the instrumental figures in helping the USSR work on atomic energy:

John Cairncross: 

John Cairncross was part of the Cambridge Five, a group notoriously known for becoming passionate communists and eventually soviet spies during and after World War II.   Cairncross, secretary to the chairman of Britain's scientific advisory committee gained access to a high-level report in the fall of 1941 that confirmed the experimentation and feasibility of a uranium bomb.   He then leaked the information to other agents who notified Stalin.  After the war in 1951, when British agents tracked down and interrogated, Cairncross' documents on the bomb were discovered.  In the end, he was not charged, but instead asked to keep quiet.  He continued denying his involvement and claimed that the information he passed on was harmless.  However, when KGB files were made public under its new democracy, Cairncross was revealed to be the agent who provided proof to Stalin that the British government was working on atomic energy and helped Soviet Russia organize and develop the work on atomic energy.

Klaus Fuchs: 

Klaus Fuchs was born in Germany and joined the Communist party as a student.  He fled to escape the rise of Nazism in 1933.  Before he became a British citizen , he had already offered to be a spy for the Soviets.  He first worked at the Los Alamos lab, handing over information about bomb construction and size (he included sketches and dimensions in his reports).  When he returned to England, to work at Britain's nuclear research facility and passed information on creating a hydrogen bomb to the Soviet union.  Although he was caught later, he sent the Soviets information describing important scientific processes related to the construction of the atomic bomb, helping the Soviets develop their own in a short period of four years.  He is considered the most important person that supplied information that helped in the building of the bomb

Theodore Hall: 

Theodore Hall was the youngest scientist on the Manhattan project.  When he was recruited to work at Los Alamos, he constantly thought of how to spare humanity the devastation of nuclear power.  In October 1944 he contacted the soviets and volunteered to tell them about the bomb research to make sure that the US didnt have too much power.  Even if they did have more power, the Soviets would know about it and would be able to recreate their own.  In December, he sent an update on the creation of the bomb, most likely the first secret of many that were divulged from Los Alamos.  Decades later, when code declassifications confirmed his spying, he said in a written statement that it seemed that an American monopoly was dangerous and should be prevented.  Therefore, he felt a duty to alert the Soviets.

Is is uncertain how many, but there are certainly more scientists and informants that contributed to the creation of the atomic bomb in the USSR.  But these men are the most infamous for supplying crucial information to Stalin, allowing him to bypass many experimental processes and expediting the quest for the atomic bomb.