Per Vic Smith:
Steel NATO cans might be rusty inside and out,

In fact, I went off of steel cans after one (that looked perfect on the
outside) rusted through over the winter and vented it's contents to the
floor of my shed/paint locker.

But from what I can read about the NATO cans - the real ones, at least -
they are coated inside as well as outside.

I guess the critical call is whether they're coated on the inside with
the same stuff as the original Jerry cans were.
--
Pete Cresswell