Israel produces tactical nukes / battlefield nukes. Would briefcase-size nukes be that more difficult?!
Regards,
“Would briefcase-size nukes be that more difficult?”
Yes. They are.
That’s why most nukes even today have fission packages that weigh quite a bit. It’s easier and cheaper to produce them and to expect them to work.
As you get smaller and smaller the refining process for the fission package becomes ever more complex. As in you need a whole different production facility and a whole different set of protocols to make these things.
The most economical of these weapons still has a fission package of more than 23 pounds with the whole device weighing in at 300 pounds or more. It’s cheaper to just produce bigger devices.