Does external threat bring the nation together? Evidence from the United States

Do external security threats unify the nation in countries with high social polarization? War and other forms of interstate competition for power may increase the salience of national identity, but the effect may be weak if the nation is divided. Empirical evidence of a trade‐off between national (superordinate) and subnational (subordinate) identification during times of crisis is sparse. We present an experimental framework to measure effects of external threat on national identification in the United States, exploring whether effects are driven by attachment to the nation (ingroup love), hostility toward other nations (outgroup hate), or both simultaneously. We find that even in a context of partisan polarization, external threat strengthens national identification, expressed mainly as increased hostility toward the national outgroup. National identification need not come at the expense of salient partisan identities as long as these are not perceived to be in competition with the national identity.