Index The Garwin Archive

Richard L. Garwin                                   March 17, 1999

    Effectiveness of Proposed National Missile Defense Against
                      ICBMs from North Korea

          (For distribution to Congress and the Press)

The  NMD  system  under  development  by  the  Defense Department,
according to Lieutenant General Lester L. Lyles, USAF, Director of
the Ballistic Missile Defense Organization (02/24/99) "would  have
as  its  primary  mission  the  defense of all 50 states against a
small number of intercontinental-range ballistic missiles launched
by a rogue nation."   But General Lyles goes  on  "Such  a  system
would  also  provide  some  residual  capability  against  a small
accidental or unauthorized launch of strategic ballistic  missiles
from  China  or  Russia.    It  would  not be capable of defending
against a large-scale, deliberate attack."

A Deployment Readiness Review is  to  be  held  in  June  2000  to
"assess  whether or not the technical progress has been made which
would allow more senior decision-makers to decide whether  or  not
we  should  commit  to  deployment,"  which decision would be made
apparently at about the same time.

But the United States should not commit to deploying a system that
will not do the job.  First, the job against North Korea or  other
emerging ICBM threat, possibly from Iran or Iraq.

In  this regard, the nation should heed the CATO Institute Foreign
Policy Briefing No. 51 of 02/11/99,

     "Rather than throw money  at  the  program--  as  would  some
     conservatives  to  whom  missile  defense  is a religion-- or
     completely avoid the missile defense issue--  as  would  some
     liberals  enamored  with  arms control for its own sake-- the
     best policy is to honestly assess the nature  and  extent  of
     emerging  threats  and  develop  a  national  missile defense
     system at a pace that the technology  can  support  and  that
     test  results  will bear out.   No matter what the threat is,
     rushing to develop a system that fails  to  work  is  not  an
     attractive remedy"

Unfortunately, the proposed NMD system would have essentially zero
capability  against the most likely emerging threat-- an ICBM from
North Korea.  And it would have strictly zero  capability  against
the  much  more  realistic  and important threat from North Korea,
Iran, or Iraq-- short-range cruise  or  ballistic  missiles  fired
from  merchant  ships near U.S. shores, a nuclear weapon detonated
in a harbor, or biological warfare agent (BW) disseminated in  the
United  States  or  from  a ship in harbor.  We will not solve our
real national security problems so long as our primary concern  is
to  deploy  a system that will not handle the threat that is cited
to motivate its deployment.  While the U.S. might be threatened to
some extent by propaganda leaflets delivered by ICBM, and somewhat
more by chemical weapons as an ICBM payload, real  strategic-level
damage would be inflicted only by BW and by nuclear payloads.

As described by General Lyles, the NMD system is intended to use a
ground-based  interceptor  launched  from  a  site from within the
United States (North Dakota or Alaska) to strike reentry  vehicles
above the atmosphere.  With North Korea as an example, in order to
be specific, these ICBMs would have been launched toward the North
in  order  to  fall on the United States.  The rocket launch flame
will be detected by the Defense Support Program  (DSP)  satellites
in  geosynchronous  orbit  within  considerably less than a minute
after launch, and an approximate location of the launch site and a
direction of the missile is established in that way.

The upgraded ground-based early-warning radars would some  minutes
later  detect  the  threat  missile and on the basis of these data
confirming the DSP information, interceptors  would  be  launched.
While  the  interceptor  is in flight, a ground-based X-band radar
with better resolution will track the reentry vehicles and to some
extent discriminate them from other objects put into space by  the
missile  (perhaps intentional decoys, certainly other parts of the
missile) to guide the  interceptor  close  enough  to  the  target
missile  for  the  interceptor's sensor to acquire the warhead and
"to discriminate the warheads from  potential  decoys."    Several
interceptors would need to be launched at each warhead in order to
achieve  the  NMD  requirement  to have high confidence in no ICBM
warheads impacting on U.S. soil.  If the system works as stated.

In July 1998, the nine-member Rumsfeld Commission  to  Assess  the
Ballistic  Missile Threat to the United States (on which I had the
privilege to serve) issued  its  unanimous  report,  judging  that
North Korea could have a true (but unreliable and inaccurate) ICBM
within  a  couple  of  years-- specifically within five years of a
decision to move forward with  a  program,  assuming  that  it  is
thoroughly  funded  with a high priority.  The Rumsfeld Commission
also advised that  there  were  other  and  earlier  threats  from
missiles  of  shorter range launched from ships, and observed also
that BW or CW agents could be packaged in  the  form  of  bomblets
released  early in flight, that would fly separately to the target

It is just this last caution which I elevate to the  status  of  a
likelihood.    It  is  far  more  effective militarily for an ICBM
payload of biological warfare agents to be arriving in the form of
individual reentry vehicles (bomblets) spread over an area  10  or
20 kilometers in extent, rather than to be delivered as 100-500 kg
of  BW  agent  at  a  single point in the target area.   Under the
latter  condition,  a  very  narrow  plume  will  be  produced  by
wind-born  BW, threatening people within the narrow plume.  But if
the same payload were dispersed in the form of bomblets,  a  large
number  of  such  narrow  plumes,  each  equally lethal within its
interior, would threaten people in the target area.

Given this undisputed  increase  in  military  effectiveness,  any
nation  with  the  capability to make an ICBM and reentry vehicles
would almost surely arrange to package  the  BW  in  the  form  of
bomblets,  released  just  as  soon  as the ICBM reached its final
velocity  on  ascent.    Placing  the  bomblets  at  predetermined
positions  in a rack within a spinning final stage, the release of
the  bomblets  would  then  allow  them  to  spread  during  their
20-minute  or  more  flight  to reentry, with the initial rotation
rate determining precisely the spread, and the pattern being  that
in  which the bomblets were stored in the missile.  This threat of
BW bomblets released on ascent is to be expected whether or not  a
defense is deployed, but the proposed NMD would have strictly zero
capability  against these bomblets.  First, there would be so many
of them (with a loading of perhaps 1 kg of agent per bomblet) that
it would exhaust any planned number of interceptors.  Second, even
with a thousand or more interceptors, it is all too easy  to  have
each  bomblet  in  a  loose-fitting and lumpy shell, just in order
that the ICBM could have deployed a vastly larger number of  empty
such  shells.    This  is  an  example  of  the  great  utility of
"antisimulation", in which the warhead itself is modified to  make
it easier to simulate by a cheap and convenient decoy.

If  North  Korea  should  manage to obtain fissile material either
from its own reactors or from abroad, so  as  to  make  a  nuclear
weapon that could be carried to intercontinental range by an ICBM,
it  would initially have what is probably an unreliable warhead on
an unreliable missile.  The warhead would be likely  to  miss  its
city  target  entirely.   But would a defense make any difference?
Yes, if the launching country cooperated, but not if it wished  to
prevent the intercept of its nuclear warhead.

Because  the  NMD  interceptors are all "hit-to-kill" so that they
must collide with the warhead in order to destroy it, the attacker
need not conceal the existence of the warhead but only  its  exact
location.  This is readily done by the use of an enclosing balloon
made  of  aluminum-foil  coated  mylar that can be put together by
anyone who buys this article of  commerce  and  spends  $20  on  a
hand-held  tool  for  heat  sealing  the  plastic  to make a large
balloon.  Even a balloon ten meters (33 ft.) in diameter, inflated
after the RV separates from the missile, would render it  unlikely
that  an interceptor would actually strike the warhead rather than
plunging harmlessly through the balloon.

The balloon would be  inflated  in  space  by  a  tiny  charge  of
gas-generating  compound  like  that found in every automotive air
bag, but instead of deploying in a 100th of a second or less,  the
balloon  could deploy in a second.  Since the launch country might
fear  that  the  interceptor  striking  the  balloon  might  cause
sufficient  disruption  to  expose  the  RV,  several  balloons in
sequence could be shrunk down on the RV  (and  would  occupy  very
little  space with the air removed by an ordinary vacuum cleaner).
So each would be ready for deployment to hide the RV once again in
case the balloon was intercepted.

Alternatively, the launching country could deploy ten or more such
balloons over a region 10 km or more  in  extent,  so  that  these
would  need  to be attacked one at a time.  Even the dynamics of a
balloon bouncing around over an enclosed object could be simulated
in the  decoy  balloons  with  an  enclosed  object  that  weighed
extremely  little in that case-- a heavier, small balloon just big
enough to enclose the RV.

The interceptor would normally  track  the  RV  by  means  of  its
infrared (heat) emission and it could readily distinguish an empty
balloon from a balloon containing the RV, simply because the empty
balloon  would  be colder, while the RV would not have had time to
cool off during its 30 minutes or less  of  flight.    But  highly
reflective  aluminum not only reflects light (and infrared) but it
correspondingly radiates a lot less-- about  30  times  less  than
does  an  unprepared surface.  Furthermore, multi-layer insulation
is an article of commerce that can  reduce  the  emitted  heat  by
another  factor 50 or more.  Finally, if the decoy maker wished to
have even greater confidence that sensors would  not  be  able  to
discriminate the decoy balloon from the balloon containing the RV,
a  small  chemical heat source could be used to mimic the 40 watts
of heat that would be emitted by the reentry vehicle  shrouded  in
multi-layer insulation within its own balloon.

These  achievements are easy relative to the scale and cost of the
effort required to develop an ICBM, and if a country  expects  the
United States to have this NMD at the time of its first ICBM, then
I  am  confident  that  these  countermeasures  can  and  will  be

But how about the observation that the  NMD  "would  also  provide
some   residual   capability   against   a   small  accidental  or
unauthorized launch of strategic ballistic missiles from China  or
Russia."    This  is  not just an "observation"; I believe it is a
requirement.  It is a very strange formulation for a  requirement;
"the  system  should provide ..." or "the system must provide ..."
would be more usual.  So it is a requirement  masquerading  as  an
observation.   As such, it is sure to provoke decoy responses that
will vitiate the system, so long  as  China  and  Russia  maintain
weapons with the intention of striking the United States either in
response to a U.S. strike on their territory or otherwise.

The  extension  of  the  deployment  date of NMD from 2003 to 2005
would not help to improve the effectiveness of  the  system.    It
might  reduce the risk of deploying some kind of system that would
work against a cooperating threat from "extremely high  risk"  (as
the  2003  deployment  has been characterized by General Lyles) to
"very high risk", but it would not solve these problems.

I believe that no deployment decision should  be  made  (and  less
development money should be spent) until one has a proposed system
that can cope with the threat.

BMDO  has  a  structured  program for considering countermeasures,
which has  the  result  that  effective  countermeasures  are  not
considered until a system of defense is available to counter them.
But  as  Churchill once observed, "Occasionally it is necessary to
take the enemy into account."

The U.S. is not helpless against these threats.   It can  and  has
done  a lot to deter the development of the threat, the deployment
of such capabilities, and even the use of  deployed  capabilities.
Of  course,  showing  great  fear  and  concern  simply raises the
bargaining value of one or a few ICBMs in North  Korea,  Iran,  or
Iraq.   Certainly in North Korea they are vulnerable to preemptive
strike by non-nuclear means, and, once used, any remaining weapons
would almost certainly be struck by nuclear weapons.

Against BW, passive protective means can do a lot-- by maintaining
positive  pressure  of  filtered  air  in  homes,  business,   and
factories, either at all times or on warning of attack.  With ICBM
delivery,  we  would  know  where and when reentry took place, and
with proper planning and investment could  counter  not  only  the
threat of BW delivered by ICBM but also by short-range missiles or
even by dispersal from a car or truck.

Finally,  it  is  entirely possible (especially with North Korea's
launch of ICBMs) to destroy the  weapons  by  intercept  in  boost
phase--  while  the  first,  second, or third stage of the ICBM is
still burning.   DSP (or beginning  in  2004  its  successor,  the
Spaced-Based  Infrared  System--  SBIRS-high)  would  provide data
accurate enough so that no radar would be necessary or  any  other
aid  to  the  interceptor.    But the interceptor would have to be
launched from a site sufficiently close and have sufficiently high
performance in order to reach  the  missile  while  it  was  still
burning.    Furthermore,  the interceptor could not simply home on
the flame but in the late stages of intercept would need  to  look
"ahead" of the flame, in order to strike the solid missile and not
sail  harmlessly  through  the tenuous flame.   This could be done
either by blind reckoning because of the known shape of the flame,
or by actual detection of the solid missile with a  proper  design
of the interceptor seeker.

Because  of  the  vast  ocean  area east and north of North Korea,
North Korean ICBMs aimed at the United States are an ideal  target
for  ground-based  boost-phase intercept.  Specifically, it should
be possible to use an interceptor of the same gross launch  weight
as  the  GBI  of the NMD program (about 14 tons, with 12.5 tons of
solid fuel) to boost the kill vehicle (of perhaps 60 kg  mass  and
containing  some  15 kg of liquid fuel) to a speed similar to that
of the ICBM-- 7 km/s, but with  larger  engines  relative  to  the
mass,  so  it  will  reach its final speed more rapidly.  A simple
calculation shows that the sea-based interceptor could be deployed
as much as 2100 km downrange from the launch  site  and  still  be
able  to  catch  the  ICBM while it is still burning.  We assume a
burn time of 250s to ICBM speed  of  7 km/s  (an  acceleration  of
three  times  that  of  gravity--  "3 g")  while  the  interceptor
receives 7 km/s in 100 seconds, so an average acceleration of 7 g.
Because  the  interceptor  must  rise  vertically  in  the   lower
atmosphere,  it probably moves only about 250 km toward its target
while it is burning, and then in the remaining  (250-100)  seconds
moves  some  1050 km.    So  in  the  burn  time  of the ICBM, the
interceptor can reach out a total of 1300 km from its launch site.
The ICBM at an average speed of 7/2 = 3.5 km/s into 50s  moves  no
more  than  875 km from its launch site.  The interceptor could be
deployed as much as 1300 km (to be practical, use 1100 km) east or
west of the ICBM trajectory,  about  800-1000 km  downrange.    So
there  is  plenty  of  room  for  U.S.  navy  ships to carry these
interceptors. The ships need have no missile-tracking radars.

Such a sea-based boost-phase intercept  system  is  not  compliant
with  the  1972 ABM Treaty, but Russia and the three other parties
to the Treaty might well agree to a specific exception, especially
if this were combined with progress on  lower  missile  levels  in
Russia and the United States.

Richard L. Garwin