Country of origin
Number of MIRVs
8 x 475 kT
Range (full load)
7 800 km
Range (reduced load)
12 000 km
Astro-inertial with GPS
D5, or Trident II, is a Submarine-Launched Ballistic Missile (SLBM).
It is an improved version of the previous Trident C4 with
greater payload, range and accuracy. It was first deployed in 1990.
These Intercontinental Ballistic Missiles (ICBMs) are used by the
United States and the United Kingdom. The US Trident II missiles are
carried by 14
class submarines, while the British missiles are carried by 4
Vanguard class submarines.
II is a three-stage solid propellant missile. It has a range of 7 800 km with full load and 12 000 km with
reduced load. So even though the Trident II does not have the
longest range comparing with other ICBMs, submarines armed
with these missiles can always approach their targets in order to reduce
their flight range.
II is a Multiple Independently-targeted Re-entry Vehicle (MIRV)
system. The missile has a throw weight of 2 800 kg. Each US
Trident II missiles can carry up to 14 warheads with a 475 kT yield
each. Each warhead weights 175 kg. Though START I agreement between
the US and Soviet Union reduced this number to 8. In 2010 a
follow-up agreement was signed between US and Russia. It is called
the "new START". So
currently the US Trident II missiles are armed with 8 warheads with
a 475 kT yield each. Re-entry
vehicles maneuver in order to avoid enemy air defenses. Each
re-entry vehicle is targeted independently.
British missiles use
different locally built warheads. Under a 1958 agreement the USA
supplied UK with blueprints of their warhead design. But the design,
production and maintenance of the UK warheads are purely UK
responsibility. Furthermore the UK was not limited by the nuclear
treaties and was capable of developing improved versions of these
warheads on their own. The British Trident II missiles reportedly carry up to 12 warheads per missile.
Maintenance of the British missiles occurs in the US. However, the
UK Atomic Weapons Establishment at Aldermaston undertakes all the
design, construction, installation and maintenance of the warheads.
II is a very accurate missile. It has a CEP of around 90 m. It is
guided on the target by astro-inertial navigation system, but can
also receive GPS updates.
II missile not only has impressive range, great payload and is very
accurate. Another major advantage of the Trident II over other
ballistic missiles is that it is submarine-launched.
It makes these ICBMs extremely deadly. At the same time positions of
stationary silo-based ballistic missiles are known and are targeted
by hostile nuclear missiles. So ballistic submarines with Trident II
missiles have a high probability of surviving the first strike, once
the country has been attacked.
Each US Ohio
class submarine carries 24 of these missiles. Because of their
longer-range Trident II missiles, the Ohio class boats have patrol
areas in waters either close to the US or in the remoter parts of
the World's oceans, making virtually impossible effective
anti-submarine measures, the more so as the boats, are acoustically
very quiet. It is worth noting that USA controls most of the World's
water area with its fleet. It allows these submarines to remain
undetected on their detterence patrols.
Vanguard class boats carry 16 missiles. Each Vanguard-class
submarine can carry a maximum of 192 nuclear warheads, although the
Royal Navy originally insisted that each boat would carry no more
than 96, deployed across eight missiles. Since the Strategic Defense
Review, this has been further reduced to 48 warheads per boat,
spread across four missiles. Although the Ministry of Defense
refuses to comment on how many missiles are deployed when a boat is
on patrol, it has indicated that the complement of Trident II
missiles now only carries one warhead per missile, which is probably
in the sub-strategic kiloton range. A single Vanguard class boat is
on deterrence patrol at any one time, and a reserve boat is also
planned that upgraded versions of the Trident II missiles will
remain in service until 2042.