Article 18 — Modification of framework agreements or contracts

1. Where activities, expenditures and measures related to defence products are implemented through the methods referred to in Article 13(8), first subparagraph, point (b) or point (c), within the Union, the rules provided for in paragraphs 2 to 4 of this Article shall apply to an existing framework agreement or contract that has as its object the purchase of defence products, which is used in that implementation method, and which does not provide for the possibility to substantially amend it. When applying paragraphs 2 and 3 of this Article, the contracting authority that concluded the framework agreement or contract shall obtain the prior agreement of the undertaking with which it has concluded that framework agreement or contract. 2. A contracting authority of a Participating Member State may modify an existing framework agreement or contract for defence products, where that framework agreement or contract has been concluded with an undertaking complying with criteria equivalent to those laid down in Article 13(4) and (5) of this Regulation, in order to add Ukraine as a party to that framework agreement or contract. 3. By way of derogation from Article 29(2), third subparagraph, of Directive 2009/81/EC, a contracting authority of a Participating Member State may make substantial amendments to the quantities set out in a framework agreement or contract, with an estimated value above the thresholds laid down in Article 8 of Directive 2009/81/EC, where that framework agreement or contract has been concluded with an undertaking that complies with criteria equivalent to those laid down in Article 13(4) and (5) of this Regulation, and insofar as the modification is strictly necessary for the application of paragraph 2 of this Article. 4. For the purpose of calculating the value referred to in paragraph 3, the updated value shall be the reference point when the contract includes an indexation clause. 5. A contracting authority which has modified a framework agreement or contract in the cases referred to in paragraph 2 or paragraph 3 of this Article shall publish a notice to that effect in the Official Journal of the European Union in accordance with Article 32 of Directive 2009/81/EC. 6. In the cases referred to in paragraphs 2 and 3, the principle of equal rights and obligations shall apply between the contracting authorities which are party to the framework agreement or contract, in particular regarding the cost of additional quantities procured.