UN Secretary General Ban Ki-moon says Syrian militants’ use of chemical weapons may weaken the “taboo” against the use of such banned agents.
In a letter sent to the United Nations Security Council on Monday, Ban said he is extremely worried that the use of chemical weapons could become "normalized in this or any conflict, present or future."
The letter was written in relation to a report from the Organization for the Prohibition of Chemical Weapons (OPCW) covering the period from September 23 to October 22, when it was investigating the use of chemical agents in Aleppo by the request of the Syrian government.
"It is imperative that those responsible for the use of chemical weapons should be held accountable," said Ban.
In the report, OPCW Director General Ahmet Uzumcu stressed that the “intensity of the ongoing conflict in Aleppo is a major challenge" to the organization’s work.
He noted that the OPCW will continue its work with Syrian authorities to further its investigations.
On October 30, some three dozen people were poisoned by a barrage of shells loaded with poisonous gas which was launched by militants against two residential neighborhoods in Aleppo.
On September 16, at least eight people, including five civilians, suffered breathing difficulties after Daesh terrorists fired mortar shells containing toxic gases at Harbal and Um Hosh towns north of Aleppo.
At least five people were also killed and a number of others affected on August 2, when artillery shells containing poisonous gases slammed into the Old City of Aleppo.
The foreign-sponsored conflict in Syria, which started in March 2011, has claimed the lives of more than 400,000 people, according to an estimate by the UN.