During the war, Iran was a victim of terrorism and chemical weapons. In spite of this, the founder of the Islamic Republic showed his great opposition to manufacturing of any kind of Weapons of mass destructions (WMD) or nuclear arsenals even for defensive purposes.
Imam believed that justice cannot be implemented by modern weapons which bring mass destruction and kill a large number of men whether they are guilty or not.
In addition, we should consider that some soldiers attend the war out of compulsion so that they are always ready to surrender themselves. Therefore, usage of mass destruction weapons is opposed to basic rules of humanity.