In message
"Clive Coleman." wrote:

In message , Graeme Wall
writes
As for the SLBMS I'm not sure the Americans can physically
prevent us launching them, we sure as hell can't stop them launching
theirs. The only way a genuine twin key approach can work is if RN boats
carry USN personnel on every deployment and I'm not aware that that is
the case.
I watched a programme years ago on a channel like National Geographical,
and if I remember, the sub had to be in contact (radio wise) with the
white house and unless they entered the right code into the system, it
won't work. Things might have changed, but I somehow doubt it.

Thay's for USN boats, RN boats have to be in contact with Northwood and
thence to Downing Street. Exactly how they get their launch codes is, for
obvious reasons, not widely advertised. However there is alldgedly a back-up
plan whereby a boat captain can launch on his own initiative if they fail to
get the shipping forecast. The twin key system here is that both he and his
first officer have to enter their own codes in order to arm the launch
system.

--
Graeme Wall
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Transport Miscellany at http://www.greywall.demon.co.uk/rail/index.html