The Center for Defense Information (CDI) claims that a detailed training replica–with dummy explosives and no fissionable material–was routinely concealed inside a briefcase and hand-carried on domestic airline flights in the early 1980s.

While the explosive power of the W54–up to an equivalent of 6 kiloton of TNT (though the more common yield was much lower)–is not much by the normal standards of a nuclear weapon (the bombs dropped on Hiroshima and Nagasaki at the end of World War II were around 16 to 21 kilotons each), their value lies in their ability to be easily smuggled across borders, transported by means widely available, and placed as close to the target as possible.

In nuclear weapon design, there is a trade-off in small weapons designs between weight and compact size.
Extremely small (as small as 5 inches (13 cm) diameter and 24.4 inches (62 cm) long) linear implosion type weapons, which might conceivably fit in a large briefcase or typical suitcase, have been tested, but the lightest of those are nearly 100 pounds (45 kg) and had a maximum yield of only 0.19 kiloton.

The largest yield of a relatively compact linear implosion device was under 2 kilotons for the cancelled (or never deployed, but apparently tested) US W82-1 artillery shell design, with yield under 2 kilotons for a 95 pounds (43 kg) artillery shell 6.1 inches (15 cm) in diameter and 34 inches (86 cm) long.


wikipedia.org/wiki/Suitcase_nuclear_device clik here