It's not a MAD world?

I am not entirely clear as to why North Korea might wish to lob an inter-continental ballistic missile (assuming that it actually had the capacity) in the direction of the UK, but Mr Cameron obviously takes the matter seriously:

David Cameron has warned against abandoning Britain's Trident nuclear submarine programme, claiming it would be foolish to do so due to the threats posed by North Korea.

The prime minister said the country should not be left defenceless when the "highly unpredictable and aggressive" regime in North Korea was developing ballistic missiles that he claimed could threaten Europe.

Writing in the Daily Telegraph,, Cameron said the UK needed to maintain the ultimate deterrent as much today as during the cold war.

"The Soviet Union no longer exists. But the nuclear threat has not gone away. In terms of uncertainty and potential risk it has, if anything, increased."

Cameron said Iran was continuing to defy the will of the international community over its nuclear programme while North Korea may already be building a nuclear arsenal.

"Last year, North Korea unveiled a long-range ballistic missile which it claims can reach the whole of the United States. If this became a reality, it would also affect the whole of Europe, including the UK."

I had been under the impression that Trident was supposed to be a deterrent; they would not obliterate us if  we did not obliterate them.  Given the threats to nuke our cousins across the Atlantic, North Korea clearly does not subscribe to that theory.  In these circumstances, what is the point of Trident?  Would it not be better to invest in one or two of these anti-missile systems that the yanks have sent to Guam?  Bound to be cheaper than Trident.