The use of force to permanently displace ethnic groups and claim their land, a form of “ethnic cleansing”, is a recurring phenomenon with grave humanitarian costs. Examples around the globe show that perpetrators frequently displace members of ethnic groups who have kin communities in neighbouring states. However, existing literature on causes of ethnic forced displacement focuses on domestic factors, while determinants across borders are not well understood. This article addresses this gap and investigates how cross-border links of ethnic groups affect their risk of being permanently displaced with force. I argue that politically excluded ethnic groups with cross-border links can be perceived by governments as both political and territorial threats. This is because such groups may use support from kin communities to organise rebellion (political threat) and make demands for secession (territorial threat). Governments likely seek to remove this “double threat”, which increases the risk of forced displacement in areas of excluded ethnic groups with cross-border links compared to areas where groups have no such links. This risk is exacerbated if kin communities gain political and economic power in neighbouring states. To test this argument, I use a novel dataset with geo-located events of ethnic forced displacement in Africa, the Middle East, and Asia (1990-2021). Evidence from staggered difference-in-differences models shows that ethnic groups with powerful cross-border kin are indeed more likely to be forcibly displaced than groups without such links. These findings imply that policies to mitigate forced displacement along ethnic lines need to take cross-border dynamics into account.