kleinbl00, this will interest you if you haven't read about it already.
Yeah, it's interesting. I was aware they'd messed around with them, but in amongst the nuclear community it was a foregone conclusion that anything you can carry is nothing worth bothering with.
I think it's interesting how they chat this up like people were deadly serious about it, when in fact it was the Army being ridiculous. They already had the 388, which everyone knew was worthless bullshit, and which didn't lob the stupid thing far enough away to bother with. Nuclear policy was essentially being dictated by Curtiss LeMay, who knew damn well that anything worth nuking was worth nuking from the air (or space). Besides which, at the time the devices were prevalent the Army had Pershing Missiles. I mean, if you want to take out a "heavy water factory" (in '61! SRSLY!) and you happen to be the Army, you push a button. It's done in under ten minutes. You don't have to rely on a team of grunts being able to keep a trash can full of plutonium out of sight while they schlep across the Sudetenland in the dark. Even their saying "nuke'em til they glow then shoot 'em in the dark" was lifted from the Strategic Air Command. Yeah, the Army Special Forces had visions of being relevant, but American SF in general weren't particularly relevant in the '60s.
Just 'cuz you took the tail off a recoilless rifle round doesn't mean you've got a backpack nuke. If you want to drop a kiloton of ordnance on something in 1961, throw a Snark at it. That's the whole point of "deterrence" - you want them to know you're coming.