Keating underscores it:

Both Russia and the United States have more than 20 years of technical experience in chemical weapons destruction, but as I noted yesterday, both countries’ efforts to destroy their Cold War-era stockpiles have been years behind schedule. Sometimes these delays are political—public protests in the United States prompted a shift from incineration to chemical treatments at several U.S. facilities—but often they’re due to the understandable technical challenges of disassembling some of the deadliest weapons ever created.

Mark Thompson goes into detail on US efforts to dispose of its own CW stockpiles:

It has taken the Pentagon far longer (the original completion date was 1994), and cost far more money (the original estimate was between $1 billion and $3 billion), to destroy its chemical weapons.

To date, the U.S. has destroyed, primarily by burning, 89.75% of the arsenal at seven of those nine [chemical weapons] sites: Johnston Island in the Pacific; Anniston, Ala.; Pine Bluff, Ark.; Aberdeen, Md.; Umatilla, Ore.; Newport, Tenn.; and Tooele, Utah. The remaining 10% is slated to be neutralized using new techniques. Current plans call for the 8% of the original stockpile remaining at Pueblo, Colo., to be rendered safe using a biotechnological process by 2019, while the 2% at the Blue Grass, Ky., is scheduled to be to be neutralized using what the Pentagon calls “super-critical water oxidation” by 2023.

Yochi Dreazen looks at how hard destroying CWs has been in Libya:

[Cheryl Rofer, who supervised a team responsible for destroying chemical warfare agents at the Los Alamos National Laboratory,] noted that Syria has far more chemical weapons than Libya, so getting rid of them could take even longer. “I wouldn’t be surprised to see this last as long as ten years,” she said.

If the U.S. and Syria came to a deal — a very, very big if — there would still be one major wrinkle. Rofer said that the only two organizations who really know how to get rid of chemical weapons are the Russia and American militaries. Given the amount of time it would take to build and then operate the disposal facilities, those specially-trained troops would need to stay in Syria for years. In a war-weary U.S., keeping that many boots on the ground for that long would be an extremely hard sell.

Larison agrees:

When we consider how adamant most Americans and even most members of Congress have been that the U.S. avoid sending ground forces into Syria, it is obviously a non-starter in Congress and with the public to suggest that American soldiers be sent into Syria for years as part of a weapons disposal effort. Such a scenario disturbingly echoes the mistakes of the Lebanon and Somalia missions. Then again, why would the Syrian government accept American soldiers on its territory for any reason? Considering how ineptly the administration has justified its proposed attack on Syria, I don’t see how they could possibly persuade Congress or the public to support what would prove to be a much longer, more significant commitment than the “unbelievably small” attack they had been advocating earlier.