The country had until Sept. 30 to eliminate its stockpile under a deadline set by the Chemical Weapons Convention.
It closes a deadly chapter dating to World War I.
The State Department said Washington would "respond quickly and appropriately" if Assad was found to have launched a chemical weapon attack.
President Trump says he’s considering a retaliatory attack on Syria, after dictator Bashar al-Assad used chemical weapons on his own people.
The U.S. has resettled only 44 Syrian refugees since October.
Banned under international law, chemical weapons are still making it onto the battlefield today. This is how their use developed throughout the 20th Century, before being deployed in Syria.
Here’s how the 45th President has spent his first 100 days in office.
Here’s how the Syrian civil war unfolded, leaving 500,000 dead and displacing millions of refugees over 6 years.