Соответствующая норма
Kampuchea
Practice Relating to Rule 74. Chemical Weapons
In 1980, the Ministry of Foreign Affairs of Kampuchea deplored the fact that “the Vietnamese army is increasingly resorting to toxic chemical products. In addition to the air-spreadings of these toxic chemical products, the Vietnamese army has conducted the systematic shellings of poison gas in every place.” 
Kampuchea, Ministry of Foreign Affairs, Statement of 5 February 1980 on the intensification by Hanoi in using chemical weapons and committing other criminal activities to exterminate the Kampuchean people, Press Release of the Permanent Mission of Kampuchea to the United Nations in Geneva, No. 21/2/80/E, 21 February 1980.
In 1987, during a debate in the First Committee of the UN General Assembly, Democratic Kampuchea stated that it was committed to a global ban on chemical weapons. 
Democratic Kampuchea, Statement before the First Committee of the UN General Assembly, UN Doc. A/C.1/42/PV.13, 20 October 1987, p. 33.