Annex A
MAKING TRIDENT MORE USABLE AND MORE THREATENING—TECHNICAL
TRANSFORMATION
21. The years since the end of the Cold
War have seen major technical changes to the Trident system. These
have been partly driven by the US nuclear weapons laboratories,
whose current annual budget of $6 billion massively exceeds the
Cold War average of $3.8 billion.
22. These changes are often justified by
the need to maintain the safety of the stockpile, and also to
ensure that, if used, the warheads would be less indiscriminate
(they would destroy military and political targets while killing
fewer civilians). The latter point represents an attempt to mollify
public hostility to any first strike against a non-nuclear state.
23. The changes made also mean that the
upgraded Trident can better fit the USA's and UK's new post-Cold
War objectives: specifically, it can hit targets across the globe
and be rapidly retargeted at mobile missiles and other shifting
targets. The key changes to the UK Trident system are as follows:
24. Extending the number of targets
and rapid retargeting. The US Submarine-Launched Ballistic
Missile Retargeting System (SRS) enables Trident submarines "to
quickly, accurately and reliably retarget missiles to targets",
and allows "timely and reliable processing of an increased
number of targets". The system allows the USA rapidly to
produce a nuclear attack plan using a small number of Trident
warheads in a regional operation. The UK has purchased the fire
control system, used to assign targets to the warheads on the
submarines, at the core of SRS, and this has been installed in
UK Trident submarines.
25. Single-warhead missiles. In
1993 Malcolm Rifkind argued that a hostile leader might gamble
that the UK would never use Trident to secure its vital interests
because of the public outrage that would follow a full-scale Trident
attack. He therefore recommended the development of a "sub-strategic"
Trident. This "sub-strategic" mission was first deployed
on HMS Victorious in December 1995 and involved fitting some missiles
with only one warhead.
26. Low-yield warheads. UK Trident
may also have been made more "usable" by reducing the
yield of the warheads. On 19 March 1998 the Secretary of State
for Defence, Mr George Robertson, in reply to question by Ms.
Roseanna Cunningham MP, stated that "The UK has some flexibility
in the choice of yield for the warhead on its Trident missile."
This flexibility may be intended to help fulfil the sub-strategic
mission. A lower yield can be achieved by detonating only the
atomic bomb part of the weapon, making it an atomic fission weapon
rather than a hydrogen fusion weapon.
27. Further developments now under way in
the US are also important. The close technical cooperation between
the UK and the US mean that it is very likely that what is being
developed in the US will later be adopted by the UK.
28. The US nuclear laboratories are continuing
to develop the Trident system in ways that facilitate its use
against targets across the globe. In 2005 the US Treasury allocated
$1.7 billion for the development of the Trident D5 missile alone.
Programmes under way include:
29. Reducing the yield of the W76 warhead.
There appears to be a current programme to reduce the size of
the nuclear explosion produced by the US W76 warhead. According
to a July 2005 report in the Santa Fe New Mexican newspaper,
the W76 is being modified so as to reduce its yield by 40% to
60 kilotons.
30. Improving the W76 warhead's ability
to destroy hardened targets. If Trident's warhead could be
made to explode close to the ground, then a low yield warhead
could be used to destroy hardened targets such as missile silos.
To achieve this the USA is seeking to give the W76 warhead a radar
arming, firing and fusing mechanism similar to those fitted to
the W88, which already has such a capability.
31. Improving the D5 missile's accuracy.
If Trident was made more accurate, then a lower-yield warhead
could be used to destroy a wide variety of targets. Recent years
have seen a number of projects underway to give Trident "GPS-like
accuracy" (about 10 million). The idea is to use GPS and/or
inertial guidance to steer a manoeuvrable re-entry vehicle to
its target. Manoeuvrability will be achieved either by adding
controllable flaps or a moveable inside weight to the re-entry
vehicle. Lockheed Martin has also sought to develop the idea that
a super-accurate Trident could be used with a conventional warhead
to destroy hardened targets.
32. These programmes are already becoming
reality. The US Congress withdrew funding from the Navy's programme
to improve the D5 missile's accuracy, but the Navy has been able
to continue it using other funding, and in March 2005 the USS
Tennessee carried out a test of a new re-entry vehicle with
flaps and GPS guidance.
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