After 1946 the United States and Britain began implementing an elaborate covert plan to overthrow Albania's communist regime by backing anticommunist and royalist forces within the country. By 1949 the United States and British intelligence organizations were working with King Zog and the fanatic mountain men of his personal guard. They recruited Albanian refugees and émigrés from Egypt, Italy, and Greece; trained them in Cyprus, Malta, and the Federal Republic of Germany (West Germany); and infiltrated them into Albania.
Guerrilla units entered Albania in 1950 and 1952, but Albanian security forces killed or captured all of them. Kim Philby, a Soviet double agent working as a liaison officer between the British intelligence service and the United States Central Intelligence Agency, had leaked details of the infiltration plan to Moscow, and the security breach claimed the lives of about 300 infiltrators.
A wave of subversive activity, including the failed infiltration and the March 1951 bombing of the Soviet embassy in Tiranë, encouraged the Albanian regime to implement harsh internal security measures. In September 1952, the assembly enacted a penal code that required the death penalty for anyone over eleven years old found guilty of conspiring against the state, damaging state property, or committing economic sabotage.