4. In the case of cross-border provision of air navigation services in an airspace falling under the responsibility of another Member State, the agreements referred to in paragraph 3 shall provide for the mutual recognition of the discharge, by each of the Member States or their authorities, of the tasks set out in this Regulation and of the results of the discharge of these tasks. They shall also specify which national supervisory authority shall be in charge of the tasks set out in Article 5(1).