Given the closeness of the British-American "special relationship," the Centre inevitably suspected that some of the President's advisers sympathized with Churchill's supposed anti-Soviet plots.1 Suspicions of Roosevelt himself, however, were never as intense as those of Churchill. Nor did the Centre form conspiracy theories about its American agents as preposterous as those about the Cambridge Five. Perhaps because the NKVD had penetrated the OSS from the moment of its foundation, it was less inclined to believe that United States intelligence was running a system of deception which compared with the supposed use of the Five by the British. The CPUSAS' assistance in the operation to assassinate Trotsky, combined with the enthusiasm with which it "exposed and weeded out spies and traitors,"2 appeared to make its underground section a reliable recruiting ground. Vasili Zarubin's regular contacts with the CPUSA leader, Earl Browder, plainly convinced him of the reliability of those covert Party members who agreed to provide secret intelligence.
By the spring of 1943, however, the Centre was worried about the security of its large and expanding American agent network. Zarubin became increasingly incautious both in his meetings with Party leaders and in arranging for the payment to them of secret subsidies from Moscow. One of the files noted by Mitrokhin records censoriously, "Without the approval of the Central Committee, Zarubin crudely violated the rules of clandestinity." On one occasion Browder asked Zarubin to deliver Soviet money personally to the Communist underground organization in Chicago; the implication in the KGB file is that he agreed. On another occasion, in April 1943, Zarubin traveled to California for a secret meeting with Steve Nelson, who ran a secret control commission to seek out informants and spies in the Californian branch of the Communist Party, but failed to find Nelson's home. Only on a second visit did he succeed in delivering the money. On this occasion, however, the meeting was bugged by the FBI which had placed listening devices in Nelson's home.3 The Soviet ambassador in Washington was told confidentially by none other than Roosevelt's adviser, Harry Hopkins, that a member of his embassy had been detected passing money to a Communist in California.4
Though Zarubin became somewhat more discreet after this "friendly warning, his cover had been blown. Worse was yet to come. Four months later Zarubin was secretly denounced to the FBI by Vasili Mironov, a senior officer in the New York