In what way were julius and ethel rosenberg involved in the anti communist movement?

The married couple was said to be involved in a conspiracy to do an espionage and that they have the information about the Soviet Union's plan to use a nuclear weapon to attack the US. 
They were both sentenced to death through an electric chair. But, until their last statements, they never confirmed that they have anything to do with the crime. The public had protested for their punishment to death and believed that they were victims. However, there are still some who look forward that this must be done for the greater good of the people.