2. Any proposal to amend this Treaty shall be submitted in writing to the Secretariat, which shall circulate the proposal to all States Parties, not less than 180 days before the next meeting of the Conference of States Parties at which amendments may be considered pursuant to paragraph 1. The amendment shall be considered at the next Conference of States Parties at which amendments may be considered pursuant to paragraph 1 if, no later than 120 days after its circulation by the Secretariat, a majority of States Parties notify the Secretariat that they support consideration of the proposal. 3. The States Parties shall make every effort to achieve consensus on each amendment. If all efforts at consensus have been exhausted, and no agreement reached, the amendment shall, as a last resort, be adopted by a three -quarters majority vote of the States Parties present and voting at the meeting of the Conference of States Parties. For the purposes of this Article, States Parties present and voting means States Parties present and casting an affirmative or negative vote. The Depositary shall communicate any adopted amendment to all States Parties. 4. An amendment adopted in accordance with paragraph 3 shall enter into force for each State Party that has deposited its instrument of acceptance for that amendment, ninety days following the date of deposit with the Depositary of the instruments of acceptance by a majority of the number of States Parties at the time of the adoption of the amendment. Thereafter, it shall enter into force for any remaining State Party ninety days following the date of deposit of its instrument of acceptance for that amendment. Article 21 Signature, Ratification, Acceptance, Approval or Accession 1. This Treaty shall be open for signature at the United Nations Headquarters in New York by all States from 3 June 2013 until its entry into force. 2. This Treaty is subject to ratification, acceptance or approval by each signato ry State. 3. Following its entry into force, this Treaty shall be open for accession by any State that has not signed the Treaty. 4. The instruments of ratification, acceptance, approval or accession shall be deposited with the Depositary. Article 22 Entry into Force 1. This Treaty shall enter into force ninety days following the date of the deposit of the fiftieth instrument of ratification, acceptance or approval with the Depositary. 2. For any State that deposits its instrument of ratification, acc eptance, approval or accession subsequent to the entry into force of this Treaty, this Treaty shall enter into force for that State ninety days following the date of deposit of its instrument of ratification, acceptance, approval or accession. Article 23 Provisional Application 11