This working paper is devoted to the analysis of current influences and future possible challenges which may arise from the presence of ethnic minorities within States’ borders. The presence of ethnic minorities, as well as their influence on the behaviour of States, both on internal politics as in foreign policy, is a multidimensional issue and requires a multidisciplinary approach. However, even defining what is an ethnic minority may result in tricky outcomes. Therefore, the best practice is to analyse the issue from different perspectives and using more than one theoretical approach. Minorities are a specific concern since they can strongly influence State-State relations and require special international attention because they can easily became a cause of civil and interstate conflicts. Moreover, these kinds of conflicts easily internationalize. Minorities, are a political issue but also a subject for International Law: their search for recognition and self-determination are of great attention because of the potential multidimensional implications as the risk of secession. In a broader sense, minorities are also an interesting focal point for political philosophy which has investigated the issue of multiculturalism and “social agonism”. Moreover, many of these ethnic minorities are cross-borders minorities which is, as a matter of facts, a great question to deal with for governments and for supranational organizations which may risk to interfere with the domestic domain of States. Even if the issue of ethnic minorities influence on States behaviour in foreign policy is not largely included in recent academic literature, it is regaining prestige because of the resurgent crisis caused by ethnic polarization as for the Kurdish minority in Turkey, Iraq, Syria and Iran. Kurds will be the case study analysed in this working paper along with the Turkish reaction toward the Iraqi referendum for regional autonomy and Kurdish support in Syria against ISIS.