Iraq’s chemical arsenal was mainly destroyed in the Saddam era, although U.S. troops encountered some old Saddam-era chemical munitions during the 2003-2011 U.S. occupation.
Syria gave up its own chemical weapons, including stockpiles of sulfur mustard, under international supervision after hundreds of civilians were killed with sarin nerve gas in a Damascus suburb in 2013, an attack Western countries blame on President Bashar al-Assad’s government, which denies it.
There is no solid proof they were destroyed. An Israeli intel chief and one of Saddam's own generals claims the bulk were transferred from Iraq to Syria. Nobody knows for sure. But stockpiles of WMDs were found. Even the NY Slimes admitted as much.