The last of Syria's declared chemical weapons material was on a ship headed for destruction Monday, marking a "major landmark" in the global effort to eliminate the nation's toxic arsenal, an oversight agency said.
The action would appear to signal an end to the most controversial stage of the undertaking to eradicate Syria's once-imposing chemical weapons threat. Its stockpile included blistering agents and nerve gas and was long considered a strategic deterrent to neighboring Israel, an undeclared nuclear state.
The apparent end of Syria's chemical weapon capabilities also signals a significant foreign policy success for the Obama administration, which has resisted intense pressure for airstrikes in the country or other more robust involvement in the civil war there.
The government of Syrian President Bashar Assad agreed to destroy the chemical weapons stockpiles without direct U.S. intervention — a striking contrast to what transpired in Iraq in 2003. The George W. Bush administration launched a massive invasion of Iraq, ousting the government of Saddam Hussein, citing the threat from weapons of mass destruction, which later proved to be nonexistent.
Nonetheless, Syria will miss a June 30 United Nations deadline for complete destruction of its chemical weapons materials . As of last week, 8% of Syria's toxic arsenal had not been removed from the country. That final batch was put on the ship Monday, authorities said.
Some skeptics have alleged that Syria failed to declare a significant part of its arsenal. The government has denied holding back any chemical weapons materials.
U.S. Secretary of State John F. Kerry praised the mission to remove Syria's chemical weapons capability, while also saying that concerns remain.
"The worst of the weapons are gone," he said in a statement.
Assad acceded to the destruction last year in a deal that averted threatened U.S. airstrikes on Syria for its alleged deployment of the nerve agent sarin outside Damascus on Aug. 21. Syria has denied using chemical weapons during the more than three-year conflict.
A U.N. investigation found that sarin had been released in the attack, but it did not conclude who was responsible. Hundreds of civilians were reported killed in the attack, which remains shrouded in mystery and conflicting conclusions. Each side in the Syrian conflict has blamed the other for the world's most lethal chemical attack in decades.
Still, Syria acquiesced to a U.N. plan to eliminate its chemical stockpiles and signed on to an international treaty banning chemical weapons production and use.
Many experts were initially skeptical that the plan to destroy the arsenal was feasible, especially in less than a year — the time frame outlined in the U.N. removal scheme. That the process unfolded as Syria was engulfed in a punishing war greatly complicated matters.
More than 30 nations, including the United States and Russia — which back opposite camps in the conflict — provided aid in the landmark effort.
"Never before has an entire arsenal of a category of weapons of mass destruction been removed from a country experiencing a state of internal armed conflict," Ahmet Uzumcu, director-general of the Organization for the Prohibition of Chemical Weapons, or OPCW, said in a statement issued at the group's headquarters in The Hague.
The organization was awarded the Nobel Peace Prize last year in part because of its disarmament efforts in Syria.
The OPCW made the announcement Monday confirming that the last consignment of chemical weapons substances had been loaded onto the Danish vessel Ark Futura for shipment out of Syria.
Under the U.N. plan, much of Syria's chemical weapons production capabilities were destroyed late last year. Mixing and filling devices, specialized missile warheads, aerial bombs and other items were all rendered inoperable and reduced to scrap under OPCW supervision, the organization said.
But what remained this year was the most sensitive task: the eradication of some 1,300 metric tons of substances including mustard gas and precursor chemicals for producing sarin and VX nerve agents.
With war raging in Syria, monitors agreed that most of the material would have to be transported out of the country for its ultimate elimination, via the nation's Mediterranean port of Latakia.
The plan faced many obstacles. Syrian authorities were obliged to move tons of hazardous chemicals along roads subject to ambush from rebels. Some insurgent groups, enraged that the United States did not bomb Syria, vowed to disrupt the process. Many in the Syrian opposition resented the focus on chemical arms when conventional weapons such as bombs, artillery shells and bullets had killed many more people than chemical agents had.
"The despicable [Assad] regime and the crisis it has created remain and require our collective focus," Kerry said in the statement Monday.
Assad has blamed the United States and its allies for backing regional Islamist "terrorists," including the Islamic State of Iraq and Syria, an Al Qaeda breakaway group that gained strength amid the chaos of Syria and now threatens the U.S.-backed government in neighboring Iraq.
To expedite the process of removing chemical weapons substances, Russia provided its ally Syria with armored vehicles and other assistance.
Assad's government said delays were caused by rebel attacks and other war-related factors, including opposition shelling of Latakia. The United States and its allies, who are backing rebels seeking to overthrow Assad, accused Damascus of deliberately slowing the process.
The most hazardous chemicals are to be sent for destruction aboard a specially rigged U.S. vessel, the Cape Ray. Less dangerous materials are to be dealt with at commercial facilities in Europe and the United States.
The OPCW has noted that Syria's declared stockpiles were in line with outside estimates of the size of the nation's chemical weapons program. Still, the organization says it will work to resolve unspecified "discrepancies" in Syria's declarations, spokesman Michael Luhan said in a telephone interview.
Also unclear is the fate of a dozen former Syrian chemical weapons facilities, including hangers and underground bunkers, that must be destroyed under the international blueprint. Syrian and OPCW officials are discussing how the structures will be destroyed.
In recent months, the Syrian government and the armed opposition have exchanged allegations that chlorine gas, deployed a century ago on battlefields in World War I, had been used in Syria. Chlorine, a common industrial chemical, is not considered a chemical weapon, but international law bans the use of any toxic material on the battlefield.
The OPCW sent a team to Syria and found evidence that "irritating agents" such as chlorine may have been used. However, the organization did not indicate who may have been responsible. Its investigation into the alleged use of chlorine gas in Syria is continuing, the agency said.
Follow news out of the Middle East with Patrick J. McDonnell on Twitter at @mcdneville.