WASHINGTON Three decades after the United States started destroying its own chemical weapons, the nation's stockpile stands at more than 3,000 tons about three times what the U.S. now says Syrian President Bashar Assad controls.
Taken together, the remaining U.S. arsenal weighs about as much as three dozen Boeing 737s loaded for takeoff. And while the U.S. has made significant progress, eradicating 90 percent of the 31,500 tons it once possessed, the military doesn't expect to complete destruction until 2023.
Deadlines have come and gone, and been extended. And, like other countries, the United States has found that complying with the Chemical Weapons Convention that banned such weaponry isn't easy to do.
Now, as the U.S. and others, the steep challenges that have hindered America's efforts for a generation illustrate the daunting task of securing and ultimately dismantling Assad's stockpiles in the middle of a civil war.
As CBS News national security correspondent David Martinthe U.S. has spent $26.5 billion building incinerators in eight states and on one remote Pacific island where chemical weapons were stored.
So far, 27,000 tons of chemical agent have been destroyed. Translate that to Syria's stockpile, and it would cost about $1 billion to destroy, Martin reported. The Pentagon, of course, knew where all its chemical weapons were stored, but that's not the case in Syria.
"I would say our knowledge of the exact location of these weapons is at best imperfect at this point," Steve Bucci, who spent part of his career in Special Forces tracking Syria's chemical weapons, told Martin.
Secretary of State John Kerry and Russian Foreign Minister Sergey Lavrovto discuss how to do exactly that. They hoped to emerge with the outlines of a plan.
Although the death toll in Syria from conventional weapons has surpassed 100,000, it wasn't until the U.S. said it determined that Assad's government had used chemical weapons on a large scale that President Obama seriously threatened military action.
That's because chemical weapons, Mr. Obama says, are different.
"Men, women, children lying in rows, killed by poison gas. Others foaming at the mouth, gasping for breath," Obama, describing the Aug. 21 attack that the U.S. says killed more than 1,400 Syrians, including hundreds of children. "On that terrible night, the world saw in gruesome detail the terrible nature of chemical weapons, and why the overwhelming majority of humanity has declared them off-limits."
Left unsaid was that the remaining U.S. stockpile includes many of the same chemicals in Assad's possession. The Syrian regime has more than 1,000 tons of sulfur, mustard gas and the ingredients for sarin and the nerve agent VX, Kerry told Congress this week.
Under a tenuous diplomatic deal being coordinated by Russia, which holds the world's largest remaining chemical weapons stockpile, Syria would join the Chemical Weapons Convention, declare its stockpiles and hand them over to the international community for destruction, all to avert a punitive U.S. military strike.
It's unclear how that colossal task could be carried out when there's distrust of Syria in the international community, uncertainty about the weapons' locations and ongoing fighting between Assad's forces and rebels. The White House says it will require extensive verification to ensure that stall tactics aren't disguised as legitimate holdups.
In the U.S., those holdups have ranged from environmental delays and political opposition to technical and safety challenges to tough laws restricting the transport of chemical weapons. Likewise, it's been difficult to round up the tens of billions of dollars to pay for destroying the cache.
"All of this is a slow process," said Dieter Rothbacher, a former U.N. chemical weapons inspector who has worked in Iraq, Russia and the U.S. "Falling behind (schedule) is actually relatively easy."
The U.S. started developing chemical weapons around World War I, steadily increasing its capabilities through World War II until 1968. The stockpile grew to about 31,500 tons of sarin, VX, mustard gas and other agents, according to the Army. Russia, by comparison, has said it amassed about 44,000 tons.
The move toward destroying the United States' chemical weapons started in the 1970s, building momentum in the 1980s when Congress directed the Defense Department to start eliminating the stockpile.
That commitment became an international obligation when the U.S. signed the Chemical Weapons Convention in 1993 and ratified it four years later. That started the clock on a 10-year period in which the U.S. was supposed to destroy the rest of its chemical weapons.
The process is complex.
The two basic methods chemical neutralization and incineration both require specialized facilities. Using incineration, chemicals must be heated to thousands of degrees. Decades-old storage containers can be leaky and tough to handle. Destruction produces highly hazardous waste that must be carefully stored. And assembled weapons, like those chemicals already loaded into rockets and packed with explosives, pose their own dangers.
The Army used to destroy chemical weapons at nine sites across the country. By January 2012, troops had completed 90 percent of the job, and only two active sites now remain.
In an arid stretch of desert about 40 miles south of Colorado Springs, Colo., sits the Pueblo Chemical Depot. The Army says that's where about 2,600 tons of mustard gas is situated in projectiles and mortar cartridges. The destruction facility is finished but still being tested, with plans to start operations in 2015. The depot employs more than 900 people and is expected to end its work by 2019.
The other site, just outside Richmond, Ky., isn't as far along. The destruction plant at the Blue Grass Army Depot is only about 70 percent complete as of this summer, and the Army doesn't expect to open it until 2020. Work at Blue Grass to destroy 523 tons of nerve and blister agents stored in rockets and projectiles should wrap up by 2023, if everything goes as planned.
The U.S. has long since missed its original 2007 deadline, which was extended to 2012, then missed again. Russia is behind schedule too.
Such are the odds as the U.S. and its allies turn to Syria and demand swift, complete and verifiable action to ensure never again can Assad use poison gas.
"Under ideal conditions, complete Syrian cooperation and having a country that's ready, willing and able to receive the material, it's theoretically possible," said Greg Koblenz, a chemical weapons expert at George Mason University. "In the middle of a very brutal civil war, it's highly implausible."