Nationalism is normally directed against closest neighbors. This simple fact -- The Hated Neighbor Truism -- has important consequences, mostly overlooked in moral debates on nationalism. First, it undercuts the defense of nationalism based on the (alleged) moral worth of proximity: since nationalists hate closest neighbors, they cannot consistently rely upon such defense. Second, it blocks the usual theoretical contrast of nationalism with cosmopolitanism: the main enemies of the nationalist are not indiscriminate cosmopolitans, but the neighbor-lovers, call them "macro-regionalists". Finally, it suggests that the proper response to nationalism is a graded, region-sensitive moderate cosmopolitanism.