I guarantee if you come out to my ranch and hit an 'empty' 55 gallon gasoline bbl with a 357 mag, that it'll make a big-ol' powee, and it doesn't mean it was a Yassir smuggling barrel! That's all I'm saying.
If I was the writer of the story, and I was skeptical about the claims, I'd hedge it in EXACTLY the same manner. In other words, if the writer was convinced of the facts, he'd write in the facts...like enumerating the weapons actually found, etc.
The barrels were used as markers for the 'goods' that were underwater.