The Member States 25 March 1957, Consolidated version of the Treaty establishing the European Atomic Energy CommunityTITLE II - Provisions for the encouragement of progress in the field of nuclear energyCHAPTER 2 - DISSEMINATION OF INFORMATIONSection 3 - Security provisionsArticle 26

The communications and, where appropriate, the use referred to in this paragraph shall be subject to the measures which, under the security regulations, correspond to the security grading required by the State of origin. The communications shall in all cases be subject to the consent of the State of origin. Consent to communication and use may be withheld only for defence reasons. 3.