Spread far and wide across Syria, the chemical weapons complex of the fractured state includes factories, bunkers, storage depots and thousands of munitions, all of which would have to be inspected and secured under a diplomatic initiative that President Obama says he is willing to explore.

But monitoring and securing unconventional weapons have proved challenging in places like Iraq, North Korea and Iran — even in peacetime. Syria is bound up in the third year of a bloody civil war, with many of the facilities squarely in battlefields.

“I’m very concerned about the fine print,” said Amy E. Smithson, an expert on chemical weapons at the Monterey Institute of International Studies in California. “It’s a gargantuan task for the inspectors to mothball production, install padlocks, inventory the bulk agent as well as the munitions. Then a lot of it has to be destroyed — in a war zone.”

“What I’m saying is, ‘Beware of this deal,’ ” Dr. Smithson added. “It’s deceptively attractive.”

As difficult as it may be to reach a diplomatic solution to head off a United States strike on Syria, the details of enforcement are themselves complex and uncertain, people with experience monitoring weapons facilities said.