There's an unexpected twist in the international drama over Syria's use of chemical weapons, and for once it's a development everybody has welcomed: Thanks to an apparently off-the-cuff proposal by Secretary of State John Kerry, quickly picked up by Russia and given a tentative thumbs-up from Syria's foreign minister, there's now a promising avenue toward avoiding U.S. airstrikes on Syria.

The idea sounds deceptively simple: In return for the U.S. standing down, Syrian President Bashar al-Assad's regime will agree to turn over its stockpile of chemical weapons to international control, eventually to be destroyed. President Obama would get his primary stated goals — Syria wouldn't be able to gas its citizens again, and one of the world's biggest caches of chemical munitions would be obliterated — and no U.S. missiles would be fired.

The nascent plan seems like such a win-win that it was immediately embraced by not only Russia but also United Nations Secretary General Ban Ki-moon, Britain, China, and U.S. lawmakers. In a series of interviews Monday night, Obama said he is positively inclined toward the diplomatic "breakthrough," too, "if it's real."

That's an important "if," say Michael D. Shear, Michael R. Gordon, and Steven Lee Myers in The New York Times. Syria's approval came from Foreign Minister Walid al-Moallem, they write, and it's not clear "Moallem has the authority to commit Mr. Assad to a significant step like the international control and ultimate destruction of an arsenal that Syria has maintained in large part as a deterrent to Israel" and its unacknowledged nuclear arms.

Even if Assad agrees — and in an interview on PBS with Charlie Rose that aired Monday night, Assad wouldn't even concede that Syria has chemical weapons — the international community won't have an easy task, or a quick one. Shear, Gordon, and Myers at The New York Times point to one reason why:

The effort to police such a proposal, even if Syria agreed, would be a laborious and prolonged effort, especially since Mr. Assad's government has shrouded its arsenal in secrecy for decades. As United Nations inspectors discovered in Iraq after the Persian Gulf war in 1991, even an invasive inspection program can take years to account for chemical stockpiles and never be certain of complete compliance, something that President George W. Bush used to justify the invasion of Iraq in 2003. [New York Times]

Reuters' Phil Stewart also notes that, unlike in post-1991 Iraq, there's a "chaotic civil war" going on in Syria, making "shielding arms inspectors from violence" a tough challenge. "This is a nice idea but tough to achieve," an unidentified U.S. official tells Reuters. "You're in the middle of a brutal civil war where the Syrian regime is massacring its own people. Does anyone think they're going to suddenly stop the killing to allow inspectors to secure and destroy all the chemical weapons?"

In a best-case scenario, Assad cooperates, and U.N. inspectors find all Syria's chemical weapons and transport them to a third country for neutralization — probably Russia. But then the toxic munitions would still be around for quite a while. As The Washington Post's Anup Kaphle points out:

The U.S. started destroying its remaining chemical weapons stockpile in 1997, as soon as enough countries ratified the global Chemical Weapons Convention to put it into effect. By 2012 — when the U.S. was supposed to have finished destroying the chemical munitions, after one extension — it had destroyed only 89.75 percent of the 30,000 tons of chemical weapons it declared in 1997. Russia is still disposing of its 44,000 tons of declared chemical weapons, too.

Syria is believed to have about 1,000 tons of mustard gas, sarin, and VX nerve gas. "The Russian proposal is in its infancy," says CNN's Matt Smith, but there's some precedent in Libya's decision to renounce its chemical weapons stockpile in 2004. After Libya declared what weapons it had to the international Organization for the Prohibition of Chemical Weapons, "the agency sent its own inspectors to Libya to verify the declaration; and then its production plants were dismantled and its stockpiles began to be destroyed." The process wasn't flawless:

Two weapons plants were torn down and a third was turned into a pharmaceutical factory before the revolution that toppled longtime Libyan strongman Moammar Gadhafi in 2011. More than half of its 24 tons of mustard gas and about 40 percent of its precursor chemicals had been destroyed before the revolution halted that work, which remains incomplete. After Gadhafi's fall, Libya's new government reported finding more mustard gas and artillery shells capable of launching it. [CNN]

Of course, just because the Kerry-Russia plan is long, difficult, and full of pitfalls doesn't mean that it's not worth pursuing. Here's Josh Marshall at Talking Points Memo:

[G]etting all the regime's chemical weapons arsenal under international control would be no small achievement. Simply focusing on it would give the U.S. something to apply leverage against (something it sorely lacks at the moment) and put the Russians in an awkward spot. The introduction of foreign forces of whatever sort is always something a regime trying to remain in power seeks to avoid. It would be a development that might well be used to leverage Assad out of power. The key is that this potentially allows the U.S. to reshuffle the deck and come at the problem on terrain which is inherently more favorable. [Talking Points Memo]