The potential effectiveness of ballistic missile defenses today remains a subject of debate. After a brief discussion of terminal and boost phase defenses, this chapter will focus on long-range midcourse defenses. The problems posed by potential countermeasures to such midcourse defenses are discussed as are the sensor capabilities a defense might have available to attempt to discriminate the actual missile warhead in a countermeasures environment. The role of flight testing in assessing ballistic missile defense effectiveness is discussed. Arguments made about effectiveness by missile defense supporters and critics are summarized.

1.
G. N.
Lewis
and
T. A.
Postol
,
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,
Science and Global Security
,
8
(
2000
), pp.
315
356
. Available from: http://scienceandglobalsecurity.org/archive/sgs08lewis.pdf [Accessed 16 July 2017].
2.
Ibid.
3.
W.
Boese
,
Army Report Details Patriot Record in Iraq War
,
2003
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4.
Raytheon Company, Iron Dome Weapon System, Fact Sheet
,
2017
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5.
American Physical Society Study Group on Boost-Phase Intercept Systems for National Missile Defense
,
Report of the American Physical Society Study Group on Boost-Phase Intercept Systems for National Missile Defense: Scientific and Technical Issues
,
Washington, D.C
.:
American Physical Society
,
2003
. Available from: https://www.aps.org/policy/reports/studies/upload/boostphase-intercept.PDF [Accessed 16 July 2017].
6.
Ibid.
7.
U.S. Department of Defense
,
DOD News Briefing on Missile Defense from the Pentagon
, March 15,
2013
. Available from: http://archive.defense.gov/Transcripts/Transcript.aspx?TranscriptID=5205 [Accessed 16 July 2017].
8.
B.
Clapper
,
U.S. Hesitant in Condemning North Korean Launch
,
The Associated Press
. December 13,
2012
.
9.
G. N.
Lewis
and
T. A.
Postol
,
Video Evidence on the Effectiveness of Patriot during the 1991 Gulf War
,
Science and Global Security
4
(
1993
), pp.
1
64
. Available from: http://scienceandglobalsecurity.org/archive/sgs04lewis.pdf [Accessed 16 July 2017].
10.
Department of Defense Appropriations for Fiscal Year 2010, Hearing Before Defense Subcommittee of the Senate Appropriations Committee, 111th Congress, p. 28, June 9, 2009; Department of Defense Authorization for Appropriations for Fiscal Year 2010, Part 1, Hearing Before the Senate Armed Services Committee, 111th Congress, p.
741
, June 16,
2009
.
11.
Status of Implementing the Phased Adaptive Approach to Missile Defense in Europe, Hearing before the Subcommittee on Strategic Forces, House Armed Services Committee, 111th Congress. p.
32
, December 1,
2010
.
12.
U.S. Department of Defense, Department of Defense Off-Camera Press Briefing by Vice Admiral James Syring on Missile Defense, News Transcript, May 31, 2017. Available from: https://www.defense.gov/News/Transcripts/Transcript-View/Article/1198464/department-of-defense-off-camera-press-briefing-by-vice-admiral-james-syring-on/ [Accessed 16 July 2017].
13.
K.
Gildea
, MDA Classifies Missile Defense Flight Test Target Countermeasure Data,
Defense Daily
, May 15,
2002
.
14.
American Physical Society Study Group
,
Report of the American Physical Society Study Group
, p.
122
15.
U.S. Department of Defense, Defense Science Board
,
Defense Science Board Task Force Report on Science and Technology Issues of Early Intercept Ballistic Missile Defense Feasibility
,
Washington, D.C
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Defense Science Board
, September
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, p.
5
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16.
Ibid, p.
27
.
17.
U.S. National Academy of Sciences, National Research Council, Committee on Assessment of Concepts and Systems for U.S. Boost-Phase Missile Defense in Comparison to Other Alternatives,
Making Sense of Ballistic Missile Defense: An Assessment of Concepts and Systems for U.S. Boost-Phase Missile Defense in Comparison to Other Alternatives
,
Washington, D.C
.:
The National Academies Press
, September
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, p.
10
. Available from: http://www.nap.edu/catalog.php?record_id=13189 [Accessed 16 July 2017].
18.
A.M.
Sessler
,
J.M.
Cornwall
,
B.
Dietz
,
S.
Fetter
,
S.
Frankel
,
R. L.
Garwin
,
K.
Gottfried
,
L.
Gronlund
,
G. N.
Lewis
,
T. A.
Postol
, and
D. C.
Wright
,
Countermeasures: A Technical Evaluation of the Operational Effectiveness of the Planned US National Missile Defense System
,
Cambridge, Massachusetts: Union of Concerned Scientists/MIT Security Studies Program
,
2000
, pp
35
37
, 145-148. Available from: http://www.ucsusa.org/sites/default/files/legacy/assets/documents/nwgs/cm_all.pdf [Accessed 16 July 2017].
19.
National Intelligence Council
,
National Intelligence Estimate (NIE): Foreign Missile Development and the Ballistic Missile Threat to the United States Through 2015
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16
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20.
R. H.
Speier
,
K. S.
McMahon
and
G.
Nacouzi
,
Penaid Nonproliferation: Hindering the Spread of Countermeasures Against Ballistic Missile Defenses
,
Santa Monica, California
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,
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; Federation of American Scientists, Decoys. Available from: http://www.globalsecurity.org/space/systems/decoys.htm [Accessed 16 July 2017].
21.
C.
Desaris
,
P.
Millner
,
C.
Grabowsky
and
M.
O’Dea
,
The Ballistic Missile Defense Organization’s Consolidated Targets Program
,
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1997
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22.
D. K.
Stumpf
,
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,
Fayetteville, Ark.: University of Arkansas Press
,
2000
, pp.
200
201
.
23.
Sessler
, et. al., pp.
59
79
.
24.
Ibid, pp.
147
148
.
25.
J.C.
Toomay
,
Radar Principles for the Non-Specialist
, 2nd ed.,
Mendham, New Jersey
:
Scitech Publishing
,
1998
, p.
93
.
26.
G. N.
Lewis
,
Space Surveillance Sensors: The Pave Paws and BMEWS Radars (April 12 2012
), blog post. Available from: https://mostlymissiledefense.com/2012/04/12/pave-paws-and-bmews-radars-april-12-2012/#more-90 [Accessed 16 July 2017].
27.
General Accounting Office (GAO)
, Missile Defense: Actions being taken to address testing recommendations, but updated 
assessment needed
, GAO-04-254.
Washington, DC
: February 2004, p. 17. Available from: http://www.gao.gov/assets/250/241487.pdf [Accessed 16 July 2017].
28.
P.
Ingwersen
,
W.
Camp
, and
A.
Fenn
,
Radar Technology for Ballistic Missile Defense
.
Lincoln Laboratory Journal
,
13
(
2002
), pp.
109
148
.
29.
E.
Brookner
, Radar Imaging for Arms Control, in
K.
Tsipis
,
D. W.
Hafemeister
and
P.
Janeway
, eds.,
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,
Washington D.C.
:
Pergamon-Brassey’s
,
1986
, pp.
135
165
.
30.
U.S. National Academy of Sciences
,
Making Sense of Ballistic Missile Defense
, p.
102
31.
Fiscal Year 2013 National Defense Authorization Budget Request for Missile Defense, Hearing before the Subcommittee on Strategic Forces, House Armed Services Committee, March 6, 2012, p
152
.
32.
W.
Broad
,
Antimissile Testing Is Rigged to Hide a Flaw, Critics Say
,
The New York Times
, June 9, 2000, p. A1. Available from: http://www.nytimes.com/2000/06/09/us/antimissile-testing-is-rigged-to-hide-a-flaw-critics-say.html [Accessed 16 July 2017]. The figure is reproduced in D. Wright,
The Target Set for Missile Defense Intercept Test IFT-9, Technical working paper
,
Cambridge, MA
:
Union of Concerned Scientists
, October 11,
2002
. Available from: http://www.ucsusa.org/sites/default/files/legacy/assets/documents/nwgs/ift9.pdf [Accessed 16 July 2017].
33.
Broad, Antimissile Testing is Rigged.
34.
Ibid.
35.
D.
Wright
and
L.
Gronlund
,
Decoys and Discrimination in Intercept Test IFT-8, Working paper
.
Cambridge, MA
:
Union of Concerned Scientists
. March 14,
2002
. Available from: http://www.ucsusa.org/sites/default/files/legacy/assets/documents/nwgs/acfxoq64k.pdf [Accessed 16 July 2017].
36.
NMD Kill Vehicle Performed ‘Very Well’ in Flight Test, Officials Say
,”
Inside Missile Defense
, October 20,
1999
, p.
1
.
37.
Gildea
, MDA Classifies.
38.
Wright
, The Target Set.
39.
Broad, Antimissile Testing is Rigged.
40.
NMD Kill Vehicle Performed ‘Very Well’
.”
41.
Raytheon Kill Vehicle Destroys Target in Inaugural Test of NMD System
,”
Inside Missile Defense
, October 6,
1999
, p.
19
.
42.
U.S. National Academy of Sciences
,
Making Sense of Ballistic Missile Defense
, p.
134
.
43.
Sessler
, et. al.,
Countermeasures
;
National Missile Defense: Test Failures and Technology Development, Hearing before the House Subcommittee on National Security, Veterans Affairs, and International Relations, Committee on Government Reform, 106th Congress (2000)
, p.
119
.
44.
U.S. National Academy of Sciences
,
Making Sense of Ballistic Missile Defense
, p.
10
.
45.
Ibid, p.
134
.
46.
Ibid.
47.
National Missile Defense: Test Failures and Technology, p.
116
.
48.
U.S. National Academy of Sciences,
Making Sense of Ballistic Missile Defense
, p.
136
.
49.
Richard
Moore
,
Nuclear Illusion, Nuclear Reality: Britain, the United States, and Nuclear Weapons, 1958-64
.
Houndmills, England
:
Palgrave Macmillan
,
2010
, p.
111
112
.
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