wrote in message

On Dec 9, 5:14 pm, "Recliner" wrote:
Did you actually see the programme? In it, the nuclear bomb was
apparently squeezed into a fairly ordinary looking leather briefcase,
casually carried by someone purporting to be just another commuter.
It certainly didn't weigh 68kg, nor was it the size of a large
backpack. So my statement stands.

Right, because a commuter carrying an explosive backpack on the tube
would immediately be clocked as suspicious.
Anyway , that was 30 years ago - who knows what classified munitions
they have now that could fit in a suitcase.

In the Spooks story, this was an old Russian (pretending to be American)
bomb, placed with a sleeper. And it was in a briefcase, not a suitcase.

I suspect that there's only so far you can miniaturise a nuclear bomb.
You need a certain mass of the fissile material (presumably enriched
uranium), plus various other essential components, including shielding
and conventional explosives. The only thing that may have got smaller in
recent years is the electronics, if any.