Just adding a little more info to Doug Fitz-Randolph' post.

The 5 gal. Swiss military surplus cans are surely just the NATO
standard can and the same (except maybe for the placard) that you'll
find listed as French or British, or whatever surplus.  The flexible
pour spout needs to be the "unleaded" size for USA use, which usually
means you buy a new one 'cause that's not what NATO forces use, I
bet.  The same folks that enforce the "halogen lights are for off-road
use only" likely are the ones enforcing "gas cans must be red," but
hey ...  There are NATO-spec plastic water cans with the same styling
as these (steel) gas cans.