NATO might not be in the EU's interest as such, but it is certainly in the interest of the member states.  It is an organization that has provided security for its member states for almost 60 years and is an efficient defense organization to rely on in the future.  With the development of a multi polar world the need for security are as great as it was during the Cold War only different.  

In addition to function as a credible defense organization in is also functioning as a forum for discussion between former foes taken more seriously than other international organizations.  NATO funnel security issues within a forum that has evolved for more than fifty years an expertise that is highly relevant even today.  For those of us that are interested in good relations with the US it provides bridges across the Atlantic and thus a viable forum for resolving security disputes within a friendly framework.  

With the development of the ESDP, the successor of the ESDI under NATO, the EU can benefit from the established infrastructure and force structure of the old defense organization given the fact that the EDI is still in its infancy.  This is also the plan agreed upon by the EU and NATO concerning the NRF, which are meant to be used in NATO-led, EU-led and UN-led operations.

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