The vast network of agents, be they informants, trustees or individuals classified in several other categories in the Soviet Union and Russia, who collaborate with the Russian intelligence services domestically probably outnumber the foreigners who co-operate with the FSB/GRU/SVR today.
Russian recruiting guidelines for their intelligence personnel are a series of theoretical instructions that one must accurately follow or risk failure.
From their manual: “The recruitment of officers and agents of intelligence and other special services of capitalist states as well as members of anti-Soviet organizations is one way of intelligence penetration into intelligence agencies and agents of the enemy.”