Résumé
This research offers an analysis of the State's foreign policy from a comparative perspective, focusing more specifically on the American, British, French and Russian regimes. The approach adopted seeks to understand foreign policy within the framework of a more general reflection on power in the State. The study notes that foreign policy is a singular area of State action and, as such, fulfills an autonomous political function. This singularity entails specificities in the organization of powers within States, without calling into question their tripartite distribution, theorized by Montesquieu. Despite the preeminence of the Executive in the field of foreign policy, the latter is not entrusted to an autonomous body. In the same way, notwithstanding a weak institutional complementarity, foreign policy does not correspond to a separate legal function either. Although the specificities of political regimes do not influence the institutional organisation in terms of defining foreign policy, they represent an important factor in the varied control exercised by national parliaments.