c) Any Member State acceding to this Pact after its entry into force shall deposit the instrument of accession with the Chairperson of the Commission; d) Any State Party may withdraw from this Pact by giving a one (1) year prior notice to the Chairperson of the Commission, who shall notify all the State Parties thereof. Article | 19 This Pact shall enter into force thirty (30) days following the deposit of instruments of ratification by fifteen (15) Member States. Article 20 a) b) c) d) Any State Party may submit proposals for the amendment or revision of this Pact; Proposals for amendment or revision shall be submitted to the Chairperson of the Commission who shall transmit same to the State Parties within thirty (30) days of receipt thereof; The amendments shall be examined and approved by the State Parties, by consensus or, failing which, by two-third majority, and thereafter, the amendments shall be formally endorsed by the Assembly; The amendments shall enter into force for each State Party which has accepted it, thirty (30) days after the Chairperson of the Commission has received notice of the acceptance. Article 21 There shall be a periodic evaluation of this Pact in order to update it and to enhance its implementation. The evaluation of the Pact shall be done within the context of paragraph 36 of the Solemn Declaration on the Common African Defence and Security Policy which provide for the convening by the Chairperson of the Peace