Document Type : Original Article
The unity of two Atlantic sides from the birth date up to now passed too many ups and downs and now on it remains as one of the satiable and long life unity. After the 11 SEP, there were many tensions and challenges among the two Atlantic sides which face the future of this unity into the doubts and suspicions. From this point of view the existing and expansion of the NATO could be mention as a virtual challenge to the international relation Theory. After the collapse of the Soviet Union, two ways of thinking and ideology about NATO were raised. Neo - realist perspective , dissolution of NATO, Neo - liberalist perspective, the continuation of NATO and the expansion of it to the East but with some new geographical and topical change. With this regard, this paper tries to look to the cause of this continuation and the existing philosophy of NATO. The two perspective of Neo-realism and Neo- liberalism with the strategy of the NATO expansion to the east will be explained and analyzed.