The four-year-old civil war in Syria is escalating as weapons inspectors have confirmed that chemical weapons have been used during certain battles. The Organization for the Prohibition of Chemical Weapons (OPCW) recently confirmed that mustard gas, and quite possibly chlorine gas, has been used in the fighting since this past summer.

The chemical weapons watchdog organization definitely confirmed last week that sulfur mustard, or mustard gas, was used at least during a summer battle that took place just outside the northern Syrian city of Aleppo, according to a report from The Washington Post. The OPCW was not able to actually confirm which group of combatants had actually deployed the poisonous gas. Mustard gas produces severe burns on the lungs, eyes and the skin. The organization confirms that they found at least two people being exposed to it and that a young baby was killed by it.

The Syrian government, under the leadership of President Assad, was said to have destroyed all of the chemical weapons they had stored and stockpiled as far back as two years ago. Recently, however, Assad’s forces have been accused of using chemical weapons, chlorine gas in particular, against rival forces.

No one is certain how anyone has obtained the mustard gas, as it is a banned weapon. This does lead many analysts to consider that the civil war in Syria continues to escalate and may become even more out of control than it already is. The four-year-old conflict has killed over 250,000 and has displaced millions who have become part of the enormous migration into Europe and Scandinavia.

After the battle outside Aleppo, area doctors were confirming many cases of people having been exposed to the deadly gas. Assad and his government have staunchly maintained that they no longer have any supplies of chemical weapons or mustard gas. They assert that their previous 1,300 tons of chemical weapons had been previously destroyed in a deal Assad made with the Russians and the Americans.