15. The order of destruction of chemical weapons is based on the obligations specified in Article I and the other Articles, including obligations regarding systematic on site verification.  It takes into account interests of States Parties for undiminished security during the destruction period; confidence building in the early part of the destruction stage; gradual acquisition of experience in the course of destroying chemical weapons; and applicability irrespective of the actual composition of the stockpiles and the methods chosen for the destruction of the chemical weapons.  The order of destruction is based on the principle of levelling out.

     16. For the purpose of destruction, chemical weapons declared by each State Party shall be divided into three categories:

Category 1:     Chemical weapons on the basis of Schedule 1 chemicals and their parts and components;

Category 2: Chemical weapons on the basis of all other chemicals and their parts and components;

Category 3: Unfilled munitions and devices, and equipment specifically designed for use directly in connection with employment of chemical weapons.

 
     17. A State Party shall start:

          (a) The destruction of Category 1 chemical weapons not later than two years after this Convention enters into force for it, and shall complete the destruction not later than 10 years after entry into force of this Convention. A State Party shall destroy chemical weapons in accordance with the following destruction deadlines:

               (i) Phase 1:  Not later than two years after entry into force of this Convention, testing of its first destruction facility shall be completed.  Not less than 1 per cent of the Category 1 chemical weapons shall be destroyed not later than three years after the entry into force of this Convention;

               (ii) Phase 2:  Not less than 20 per cent of the Category 1 chemical weapons shall be destroyed not later than five years after the entry into force of this Convention;

               (iii) Phase 3:  Not less than 45 per cent of the Category 1 chemical weapons shall be destroyed not later than seven years after the entry into force of this Convention;

               (iv) Phase 4:  All Category 1 chemical weapons shall be destroyed not later than 10 years after the entry into force of this Convention.

          (b) The destruction of Category 2 chemical weapons not later than one year after this Convention enters into force for it and shall complete the destruction not later than five years after the entry into force of this Convention.  Category 2 chemical weapons shall be destroyed in equal annual increments throughout the destruction period. The comparison factor for such weapons is the weight of the chemicals within Category 2; and

          (c) The destruction of Category 3 chemical weapons not later than one year after this Convention enters into force for it, and shall complete the destruction not later than five years after the entry into force of this Convention.  Category 3 chemical weapons shall be destroyed in equal annual increments throughout the destruction period. The comparison factor for unfilled munitions and devices is expressed in nominal fill volume (m3) and for equipment in number of items.

     18. For the destruction of binary chemical weapons the following shall apply:

          (a) For the purposes of the order of destruction, a declared quantity (in tonnes) of the key component intended for a specific toxic end product shall be considered equivalent to the quantity (in tonnes) of this toxic end product calculated on a stoichiometric basis assuming 100 per cent yield.

          (b) A requirement to destroy a given quantity of the key component shall entail a requirement to destroy a corresponding quantity of the other component, calculated from the actual weight ratio of the components in the relevant type of binary chemical munition/device.

          (c) If more of the other component is declared than is needed, based on the actual weight ratio between components, the excess shall be destroyed over the first two years after destruction operations begin.

          (d) At the end of each subsequent operational year a State Party may retain an amount of the other declared component that is determined on the basis of the actual weight ratio of the components in the relevant type of binary chemical munition/device.

     19. For multicomponent chemical weapons the order of destruction shall be analogous to that envisaged for binary chemical weapons.

     20. The Executive Council shall review the general plans for destruction of chemical weapons, submitted pursuant to Article III, paragraph 1 (a) (v), and in accordance with paragraph 6, inter alia, to assess their conformity with the order of destruction set forth in paragraphs 15 to 19.  The Executive Council shall consult with any State Party whose plan does not conform, with the objective of bringing the plan into conformity.

     21. If a State Party, due to exceptional circumstances beyond its control, believes that it cannot achieve the level of destruction specified for Phase 1, Phase 2 or Phase 3 of the order of destruction of Category 1 chemical weapons, it may propose changes in those levels. Such a proposal must be made not later than 120 days after the entry into force of this Convention and shall contain a detailed explanation of the reasons for the proposal.

     22. Each State Party shall take all necessary measures to ensure destruction of Category 1 chemical weapons in accordance with the destruction deadlines set forth in paragraph 17 (a) as changed pursuant to paragraph 21.  However, if a State Party believes that it will be unable to ensure the destruction of the percentage of Category 1 chemical weapons required by an intermediate destruction deadline, it may request the Executive Council to recommend to the Conference to grant an extension of its obligation to meet that deadline.  Such a request must be made not less than 180 days before the intermediate destruction deadline and shall contain a detailed explanation of the reasons for the request and the plans of the State Party for ensuring that it will be able to fulfil its obligation to meet the next intermediate destruction deadline.

     23. If an extension is granted, the State Party shall still be under the obligation to meet the cumulative destruction requirements set forth for the next destruction deadline.  Extensions granted pursuant to this Section shall not, in any way, modify the obligation of the State Party to destroy all Category 1 chemical weapons not later than 10 years after the entry into force of this Convention.

     24. If a State Party believes that it will be unable to ensure the destruction of all Category 1 chemical weapons not later than 10 years after the entry into force of this Convention, it may submit a request to the Executive Council for an extension of the deadline for completing the destruction of such chemical weapons.  Such a request must be made not later than nine years after the entry into force of this Convention.

     25. The request shall contain:

          (a) The duration of the proposed extension;

          (b) A detailed explanation of the reasons for the proposed extension; and

          (c) A detailed plan for destruction during the proposed extension and the remaining portion of the original 10 year period for destruction.

     26. A decision on the request shall be taken by the Conference at its next session, on the recommendation of the Executive Council.  Any extension shall be the minimum necessary, but in no case shall the deadline for a State Party to complete its destruction of all chemical weapons be extended beyond 15 years after the entry into force of this Convention.  The Executive Council shall set conditions for the granting of the extension, including the specific verification measures deemed necessary as well as specific actions to be taken by the State Party to overcome problems in its destruction programme.  Costs of verification during the extension period shall be allocated in accordance with Article IV, paragraph 16.

     27. If an extension is granted, the State Party shall take appropriate measures to meet all subsequent deadlines.

     28. The State Party shall continue to submit detailed annual plans for destruction in accordance with paragraph 29 and annual reports on the destruction of Category 1 chemical weapons in accordance with paragraph 36, until all Category 1 chemical weapons are destroyed.  In addition, not later than at the end of each 90 days of the extension period, the State Party shall report to the Executive Council on its destruction activity.  The Executive Council shall review progress towards completion of destruction and take the necessary measures to document this progress.  All information concerning the destruction activities during the extension period shall be provided by the Executive Council to States Parties, upon request.