WASHINGTON — When Secretary of State John Kerry dangled for the first time on Monday actions that President Bashar al-Assad of Syria could take to avoid a military strike, it seemed an acknowledgment that Congress, America’s allies and the Russians were all looking for an off-ramp for what a week ago seemed like inevitable military action against Syria.

The concept has taken on many permutations in the past five days, but its essence is this: force Mr. Assad to turn his huge stockpile of chemical weapons over to some kind of international control and recognize the international ban on chemical weapons. The appeal of the idea is that, if successful, it could create a far more lasting solution than a brief strike on Syria’s chemical weapons infrastructure, especially a strike that Mr. Kerry characterized Monday morning as “unbelievably small.”

Yet, experts on chemical weapons and the Syrian government said that it would be next to impossible to know with certainty where all of Mr. Assad’s sprawling, constantly moving arsenal is residing, much less who is controlling it. And flying it out of the country is not as simple as picking up nuclear components — as the United States did in Libya in late 2003 — and moving them to a well-guarded site in Tennessee.

Though Mr. Kerry also expressed skepticism that the Syrians would take up the idea, his comments were notable because as recently as the middle of last week he was not talking about any diplomatic initiatives to secure the stockpile. A proposal by Senators Joe Manchin of West Virginia and Heidi Heitkamp of North Dakota, both junior members of the Democratic caucus, to give Mr. Assad 45 days to sign on to the Chemical Weapons Convention and begin to turn over his weapons had yet to catch Mr. Kerry’s attention.