'Vital and irreplaceable facilities': explaining leverage when states host great powers' spying operations.

Great powers use others' territory for spying. Existing work shows that hosts of spying sometimes enjoy high leverage over great powers in exchange for their cooperation. At other times, hosts wield less leverage. Why? This paper points to the quality of intelligence that great powers glean from a host's territory and the availability of alternatives to account for this variation. In U.S. spying on the Soviet Union from Iran, changes in these factors during the 1960s caused Iran's leverage over the United States to increase. U.S. concessions enabled the Shah's excesses. But the United States retained access to extraordinary intelligence. [ABSTRACT FROM AUTHOR]