The highest status of a diplomatic mission is the embassy, headed by an ambassador, largely replacing the prewar distinction between legations, headed by ministers, and the more senior embassies. Embassy buildings, including the ambassador’s residence, come under the protection of the Vienna Convention and invariably conceal an intelligence function, both human and technical.
Many diplomatic premises contain clandestine intercept equipment to enable skilled operators to eavesdrop on local targets, and the telltale antennas may be disguised as flagpoles or hidden inside fiberglass radomes to prevent detection from neighboring structures.
Intelligence personnel assigned to embassies mask their true role by adopting diplomatic cover, although internally the Soviet organization was known as the rezidentura, with the British and American equivalents being called stations.