The validity of Mutually Assured Destruction was unproven at the height of the Cold War. Now, in an age of asymmetric warfare and irrational "players" it won't work.
The argument goes:
"If you fire at us a nuclear weapon which will destroy us then we will fire at you a weapon which will destroy you."
"Ah. But I am going to get my reward in the next world and I'll have destroyed you. I win."
To such an idea M.A.D. means nothing.
Last weekend I was in Trafalgar Square when the demo against the Trident replacement, against attacking Iraq and for withdrawing troops from Iraq was on.
The Metropolitan Police gave reports of 2000 - 3000 people on the march.
The Stop the War Coalition reported 100,000. Given the capacity of Trafalgar Square is 50,000 and it was not full I'd say there about 20,000 to 30,000 there, tops. There's a discussion about it essentially upping the figure to agree more with the StWC here.
Here's some pictures of the demo taken on my new camera.
There was more than enough room to wander freely and swing (whatever you felt like swinging). Nobody felt squashed. It was one of the sparser attended demos I have seen.