Sultan Abdülhamid II’s (1876-1909) abrogation of the 1876 constitution soon after his installation and in the midst of the 1877-78 Russo-Ottoman war plunged the empire into a prolonged “stage of siege,” as Noëmi Levy-Aksu has described it. Constitutional rule would not be reinstituted until the 1908 Young Turk Revolution that stripped Abdülhamid II of his autocratic powers. Censorship, repression of dissent, and violence against perceived enemies of the state quickly became defining characteristics of the Hamidian era. At the same time, the late nineteenth century witnessed a dramatic increase in the numbers of Ottoman subjects traveling abroad to study, find work, or engage in trade. The Hamidian regime viewed overseas migration, especially among non-Muslim, as a threat to the empire’s domestic security. Of particular concern was the migration of Armenians from the empire’s eastern provinces, a phenomenon that Istanbul believed was inextricably linked with the simultaneous rise of Armenian revolutionary politics. Beginning in the mid-1890s, Ottoman diplomats in the United States embarked on an ambitious effort to monitor and surveil Armenian migrants living in the country. Ottoman officials were especially eager to glean information about the ways in which these migrants maintained contact with their home communities in the empire’s eastern provinces, and to monitor the movements of suspected revolutionaries. These surveillance reports contributed to the growing sense among many in the imperial bureaucracy that mobile Armenians posed a grave threat. This paper will discuss the image of the Armenian migrant as a “national security” threat in Ottoman state discourse, particularly within the context of the empire-wide state of siege that defined the Hamidian era. Further, as this paper seeks to demonstrate, anxieties about the return of Armenian migrants from North America spurred the Ottoman state to adopt strategies intended to keep such individuals from reentering the empire that over the course of the twentieth century would become staple practices of modern border security. Thus, far from being a illiberal outlier in an age of more-or-less open borders, the criminalization and vilification Armenian migrants and the increasingly sophisticated efforts that Istanbul employed to stymie their mobility foreshadowed the near universalization of anti-migrant discourses and punitive practices in the twentieth and early twenty-first century worlds.