I think you're probably right. But standard nuclear doctrine is to assume that the first strike is a decapitation attack that takes out the other side's ability to return fire, then you take out secondary targets providing infrastructure and military support, and finally - if there's anyone left to care - you take out the major political and population centres.

Nuking Washington and London with container-based H-bombs reverses that. It has the advantage that the nukees can't be sure who the enemy is - Russia, or China, or North Korea, or Iran, or India, or Pakistan, or even Israel, or even nutters on your own side.

So you can't launch a retaliatory attack without doing a lot of guessing and hoping and perhaps some hard science analysing isotope signatures and yield patterns. None of which are likely in the chaos immediately following.

So the downside is that it's not actually a decapitation. Someone nukes ten US cities with containers, what's left of the US military assumes it was Russia and/or China because why not, eh, and off it all goes.

Fallout and nuclear winter kill almost everyone, and it's not exactly a scenario made of win.

The US establishment is worried about all of this. Obama has been enthusiastically replacing nuclear command officers, for reasons that aren't entirely public.

I think it doesn't even need nukes. A massive cyber-attack is enough to take down the Internet and the utility grid in most Western countries. It's a much more immediate threat because it can be done selectively and surgically and made to look like a lot of unfortunate coincidences rather than one big ham-fisted slap down.