The head of the Organization for the Prohibition of Chemical Weapons announced on Monday it had removed the last of Syria’s declared poison gasses from the wartorn country.

Ahmet Üzümcü told reporters in The Hague the weapons had been loaded on a Danish ship and departed the Syrian port of Latakia.

The weapons are due to be delivered to the American ship MV Cape Ray, specially outfitted to destroy Syrian chemicals at sea, as well as commercial facilities in Finland, Germany, the United Kingdom and the United States.

Üzümcü cautioned he could not say for certain that Syria had declared all its poison gasses. “All we can do is work on the basis of verifying a country’s declarations of what they have,” he said.

An international effort to dismantle Syria’s chemical weapons arsenal, previously believed to be the Middle East’s largest, got underway more than a year ago when the United States said Syria had crossed a “red line” by gassing civilians. While the regime of President Bashar Assad denied using chemical weapons, it jumped on a suggestion from its ally Russia to offer to give up its arsenal to stave off Western intervention in the civil war.

Experts warned that Syria might only declare its outdated weapons and secretly keep its more sophisticated chemicals. The American Interest‘s Adam Garfinkle wrote as recently as April, “It would keep the newer, more usable and lethal munitions and con us into being a hazmat garbage collector for the rest of the militarily marginal toxic junk that had piled up over the decades — and we’d foot the bill.”

The effort also forced Western countries into a coalition with a regime they claimed to oppose, since it was the only faction in Syria capable of providing the security needed to remove the weapons.

Whatever the scale of the chemical weapons destruction, it has not stopped Assad from deploying other brutal tactics against civilians and his opponents alike, including dropping barrels bombs on populated areas and withholding food and medicine from rebel areas.

While it is impossible to say how many Syrians have died in the conflagration since early 2011, opposition groups put the total at anywhere between 110,000 and 232,000 as of May this year.