Defense

All U.S. nuclear weapons have been designed on computers.

This was true even in 1944–1945, when “computer” was a job title for

a small army of young women. Many were the wives of the scientists

and technicians designing and building the nuclear weapons. Each

of the “computer elements” operated a Marchant or Frieden

mechanical calculating machine, entering results of one or two operations on an index card and passing it on. Sometimes the choice of

which person to pass the data on to depended on the result of the

computer’s calculations. The computations required to ensure that a

modern nuclear weapon functions as desired are, in general, far too

complicated to be performed by a few people armed with nothing but

old-fashioned mechanical calculators. As the American experience

with nuclear weaponry evolved from the crude devices of 1945 to

more sophisticated designs that were lighter and more powerful and

used less uranium or plutonium, the need for fast electronic computers grew. Indeed, the nuclear weapons establishment was one of

the driving forces behind the early development of computers.

A thermonuclear weapon includes layers of materials, such as

uranium and/or plutonium, some kind of tamper or reflector material, a high explosive, boosting gas made up of tritium and deuterium, fusion fuel using lithium deuteride, and an outer casing

(radiation case) that encloses the explosive components. One

major problem in designing a device is ensuring that the shock

waves from the high explosive properly cross the boundaries

between layers and that the energy from the primary is properly

absorbed by the secondary. Matching such boundary conditions is a

Overview

All nuclear weapons now in the American stockpile were developed with the aid of computer models validated by comparison

with nuclear tests. However, those models required the use of

parameters that were not well understood and often needed

adjustment to make computation and test agree. Facing the possibility of a test ban, the Department of Energy initiated a Stockpile Stewardship Project to develop a predictive capability with

validated, physics-based simulation tools at its core. This program

is charged with maintaining the performance, reliability, and

safety of U.S. nuclear weapons without nuclear testing. To meet

the requirement for maintaining the enduring stockpile, the

Department of Energy engaged the three national weapons laboratories in creating the Accelerated Strategic Computing Initiative (ASCI). ASCI advanced computational capabilities and threedimensional models, combined with major experimental and

testing facilities, should make it possible for the United States to

maintain its present nuclear stockpile indefinitely. The authors

believe that the ASCI computational capabilities also will enable

nuclear weapon designers to draw on archived data from more

than 1,000 nuclear tests to adapt proven designs to future mission

requirements. Through extensive computer modeling and nonnuclear testing, new nuclear weapons could be designed and introduced into the stockpile, so long as the new weapons used design

concepts similar to those proven in nuclear tests.

Computer Simulation and the

Comprehensive Test Ban Treaty

by Peter D. Zimmerman and David W. Dorn

A publication of the

Center for Technology and National Security Policy

National Defense University

AUGUST 2002

Number 17

Horizons

August 2002 Defense Horizons 1

Center for Technology and National Security Policy

The National Defense University (NDU) established the Center for Technology and National Security Policy in June 2001 to study the implications of technological

innovation for U.S. national security policy and military planning. The center combines scientific and technical assessments with analyses of current strategic and

defense policy issues. Its major initial areas of focus include: (1) technologies and concepts that encourage and/or enable the transformation of the Armed Forces, 

(2) developments by defense laboratories, (3) investments in research, development, and acquisition and improvements to their processes, (4) relationships among

the Department of Defense, the industrial sector, and academe, and (5) social science techniques that enhance the detection and prevention of conflict. The staff is

led by two senior analysts who hold the Roosevelt Chair of National Security Policy and the Edison Chair of Science and Technology and who can call on the expertise

of the NDU community and colleagues at institutions nationwide. The papers published in the Defense Horizons series present key research and analysis conducted

by the center and its associate members.
Peter D. Zimmerman was chief scientist of the Arms Control and Disarmament

Agency and science adviser for arms control in the Department of State.

He may be contacted at (202) 224–4651 or via e-mail at Peter_Zimmerman@

foreign.senate.gov. David W. Dorn is retired from Lawrence Livermore National

Laboratory, where he was a distinguished nuclear weapon designer. He was 

an inspector for nuclear weapons with the United Nations Special Commission

in Iraq.

difficult computational task that is essential to success. Other tasks

for the design program include understanding how solid metal is

made to flow like a liquid or compress like a gas (that is, solving the

equation of state of the material).

Nuclear design codes may be one-, two-, or three-dimensional.

That is, they can reduce computations to the minimum by treating

each component separately and only examining what goes on along a

single line through the primary or secondary (one-dimensional); they

can examine a section through the objects

(two-dimensional); or they can model the

actual three-dimensional shapes of the primary, secondary, and radiation case. Onedimensional calculations are clearly too simplified for modern nuclear weapons;

three-dimensional codes stressed the capabilities of the largest computers in the world

only a little more than 10 years ago.

In general, nuclear weapons design

codes have been used to answer such technical questions as:

■ How does the high explosive compress the fissile material?

■ How does the nuclear chain reaction in the fission primary begin,

propagate, and die out?

■ When does “boosting” begin, and when do favorable conditions for

boosting occur?

■ After boosting occurs, how is energy produced by the primary, and

how effectively is it transported to the secondary (the “hydrogen bomb” part

of the weapon)?

■ Once the energy reaches the secondary, will the second stage function, and with what yield?

The so-called legacy design codes, written before the Department of Energy created its Accelerated Strategic Computing Initiative (ASCI) program and generally before the end of testing, explore

the explosion of a nuclear weapon in a simplified manner. They

often require the incorporation of adjustable parameters learned

from explosive nuclear testing. While the authors of the legacy

codes incorporated a great deal of detailed physics in their work,

they could not handle many of the phenomena from first principles.

The adjustable parameters were in some sense a measure of scientific ignorance about the intimate details of the physics and a

demonstration of the inability of the codes of the era to calculate

the effects of small changes (for example, in metals, structure,

explosive chemistry, and design) that might arise during the fabrication or aging processes.

Due to rapid advances in processor speed, memory speed, and

capacity, as well as the development of graphics cards and large hard

disks, the $700 computer under the average desk (2001 pricing and

specifications) is at least as powerful as the supercomputers of the

late 1980s. Two-dimensional design codes similar to the legacy codes

can be run on such machines.

Such design codes predict in simplified form what will happen

in a nuclear weapon when it functions basically as intended. They

cannot include details of nonnuclear components or even such real

and necessary features as welds, bolts, and the ancillary plumbing

required to make a real weapon. Even the most powerful computers

used to design the most modern U.S. nuclear weapons were too slow

and had too little memory to handle such

complications. Legacy codes ran on supercomputers with speeds in the range of hundreds of mega-computer operations per second (megaOPS) to a few gigaOPS; the new

generations of computers used for ASCI

have speeds between one and one hundred

teraOPS.1 While the large Cray and other

supercomputers of the 1980s and 1990s had

random access memories storing a few to a

few hundred million bytes of information, the large ASCI machines

have already reached 6.2 terabytes2 of fast memory plus 160 terabytes of disk storage space.

By 2005, the fastest ASCI machine, which will be installed at

the Los Alamos National Laboratory, will operate at 100 teraOPS. The

purpose of computers with such blazing speeds and gigantic memories is not the raw production of numbers, but, as mathematician

R.W. Hamming pointed out, to gain insight into the problem at hand.

To this end, a major part of the ASCI effort is devoted to the search

for ways to visualize the enormous flow of computed data.

Simulation of the results of time-induced changes in the

weapons of the stockpile, combined with an aggressive stockpile

surveillance program to detect those changes, is intended to provide the stewards of the nuclear stockpile with the information

needed to certify the safety and reliability of the enduring stockpile

in the absence of nuclear testing. Before President George Bush’s

1992 decision to end U.S. nuclear testing and with it the program

to develop new nuclear weapons, a suspected problem in a given

weapon could be put to the ultimate test—an underground nuclear

explosion. Testing was an option used rarely and generally only

with weapons that were already showing unmistakable signs of

problems during inspection or as a result of new computations of

the behavior of the device. It was, however, available in the case of

extreme need and was instrumental in confirming suspicions that

the WB80 air-launched cruise missile weapon would not perform

properly after becoming chilled during a long flight under the wing

of a B–52 bomber. The necessary changes were made subsequently.

American designers also did not worry about the performance

of very old nuclear weapons. It had been standard practice to retire

older weapons from the stockpile as new delivery vehicles carrying

new weapons were developed. After the Bush test moratorium was

put into place in 1992, development of a new weapon was considered

risky because it could not be subjected to a nuclear proof test.

The Role of Verification and Validation

A major goal of the ASCI program is to enhance computational

capability so that it can substitute for nuclear proof and safety testing. To give U.S. policymakers the same level of confidence in the

2 Defense Horizons August 2002

the $700 computer

under the average desk

is at least as powerful

as the supercomputers

of the late 1980s
reliability and safety of the stockpile that they would ordinarily get

from nuclear testing, the Department of Energy requires that simulation codes be both verified and validated. Neither verification nor

validation is an easy task, but both must be accomplished for ASCI to

be effective.

Verification of the code means scientists have determined that

the software implements an algorithm that correctly represents a

“model of a physical process.” It may be loosely thought of as finding

and correcting errors in the coding of the program (debugging of

code) and running check cases to ensure that the program correctly

computes the equations used in specific cases. Possible ways to verify the code include constructing appropriate software engineering

audit trails to account for changes in the code and establishing that

the computation incorporates correctly the fundamental physics

problems. Such problems will include propagation of chain reactions, thermodynamics of the primary and secondary materials, compression of boost gas and the effects on boosting of instabilities in

the pit, and the ignition of thermonuclear

secondaries. Some of these phenomena are

understood well enough to permit physicists

to compute limiting cases analytically (that

is, with pencil-and-paper mathematics that

can be evaluated without using the computer to solve equations), and sometimes

exactly. Verification requires that the simulation codes reproduce these known analytical results.

Validation is another problem entirely.

It is a process of checking to see that the

model represented by the computer code accurately represents the

real world, at least in the limited domain of the specific applications.

Validation requires the input of measured physical data, the comparison of computational results from the new codes with those of

older legacy codes, and comparison with data from actual nuclear

test explosions conducted before the end of U.S. testing. Verified

code must be validated to show that in the macroscopic world of an

actual nuclear detonation it produces results that match data from

three sources:

■ Legacy codes

■ The archived data from more than 1,000 successful and failed U.S.

nuclear explosions. Reproducing anomalies, such as primaries that failed to

reach predicted yield or secondaries that failed to burn despite proper functioning of the primary, is likely to be a more stringent test for code validation

than computing the results of tests that succeeded.

■ New data from the Dual Axis Hydrodynamic Radiographic Test Facility (DAHRT), National Ignition Facility, and other facilities giving very

detailed information on the performance of specific assemblies that can be

built in moderate numbers and tested repeatedly. Such experimental devices

can all be built alike, or anomalies such as cracks, deformations, and asymmetries, can be inserted to show the behavior of the device and the simulation systems in detail.

The verification and validation program has passed its first major

milestone, demonstrating “initial validation methodology” of the current state of ASCI code modeling for early-time primary behavior.

Not all validation of the ASCI systems needs to come from

nuclear weaponry. The problem-solving environment is applicable to

complex problems in many fields. Developers can ensure that the

underlying computational structures that translate a problem from

language appropriate to a small machine to the massively parallel

supercomputer platforms of ASCI are working properly.

Getting the Physics into the System

Until the advent of the early teraOPS machines, the details of

the performance of a nuclear weapon could only be checked in what

the weapons community called integral tests (nuclear test explosions). Over the last 5 years, the speeds of the computers built for

nuclear design (including the ASCI machines) have increased by a

factor of about 15; the increase over the last decade may be closer to

a factor of 50. Random access data storage capacity has increased at

least as much in the same period, as has the ability to build large

arrays of mass storage devices (hard disks)

at affordable cost. These computer advances

allow nuclear weapons physicists for the

first time to contemplate including accurate

models of such processes as corrosion; deterioration of materials; the effects of turbulence and “mix”;

3 the effects of small changes

in the dynamic properties of materials; and

fractures. Measuring the materials properties involved is difficult, particularly at the

small distances where previously unstudied

problems in nuclear weapons physics may

lie. A vigorous experimental program in the properties of highly

stressed materials is essential and has already begun. This program

will provide the data and validated physical models needed for simulation to be useful in examining the functioning of weapons that

show anomalies during routine surveillance of the stockpile. The

high-temperature and high-pressure properties of what the Department of Energy calls key stockpile materials have already been studied. The results were then incorporated into simulations that have

resolved, at least in part, the anomalous performance of devices

tested many years ago.

The goal of the simulation program is to provide a tool for studying the behavior of older nuclear devices, perhaps showing the effects

of corrosion, degradation of the high explosives or other composites,

cracking, and other signs of aging. Simulation can also be used to

study the behavior of nuclear weapons in abnormal environments,

such as fire or plane crashes. Experiments using simulants to replace

nuclear materials are permitted under the Comprehensive Test Ban

Treaty (CTBT), but many more cases can be run at far lower cost on

a computer than with hardware. This is a major benefit of simulation

and ASCI, not only for the nuclear weapons community but also for

other scientists and engineers. One need only think of the benefits of

being able to simulate automobile crashes including every single part

of the automobile on a computer with real accuracy.

The ASCI program is one of the most ambitious computer

development projects ever undertaken. It will increase computer

speed and capacity more than 50-fold in less than 6 years, beating

Moore’s Law which predicts the doubling of computational speed

August 2002 Defense Horizons 3

simulation can also be

used to study the

behavior of nuclear

weapons in abnormal

environments, such as

fire or plane crashes
every 18 months for single processors by about a factor of 10. This is

possible because the ASCI machines are massively parallel, being

composed of up to several thousand individual computer processing

unit chips. The fastest machine now available is the Lawrence Livermore National Laboratory (LLNL) White supercomputer, which

has achieved a speed of 12.3 teraOPS. The ASCI Q computer will use

nearly 12,000 processors and have a speed of 30 teraOPS when it is

completed in 2002.

A major factor in the success to date of ASCI is the Academic

Strategic Alliances Program (ASAP), which has brought the Nation’s

top supercomputer scientists to ASCI, leveraging their research to

strengthen its programming efforts. This effort means that a great

deal more manpower will be available for perfecting the techniques

of large-scale modeling than if only weapons scientists were involved.

The ASAP will also be an important factor in transferring the technology and techniques developed in ASCI to the private sector.

When the simulation tools have been properly validated, they

should serve as the front-line method for understanding the implications of any anomalies observed in the stockpile. The results to

date have shown that the program is on track and that it is already

very capable.

A three-dimensional simulation of

the explosion of a nuclear weapon primary was conducted on the IBM Blue

Pacific supercomputer at LLNL in 1999.

This computational experiment required

the full machine for 20 days and used

300,000 megabytes of memory.4 This

first-ever three-dimensional simulation

of a primary explosion revealed the

cause of a mysterious test failure more

than 20 years before. 

Also in 1999, the ASCI Red supercomputer at Sandia National

Laboratory completed simulations of a weapons system exposed to

blast and radiation, correctly predicting the response of the weapon

and providing tools to understand its vulnerability to a real nuclear

battlefield environment.

Los Alamos, using the Blue Mountain supercomputer in April

2000, simulated the ignition and burn of a three-dimensional thermonuclear secondary. This program ran for more than a month and

generated 15 terabytes of information. An exciting part of this simulation is that it was started on the Blue Mountain machine, ran for

820 hours, and then continued at the Sandia ASCI Red machine for

196 hours. This cross-platform result and the compatibility of the two

very different machines goes a long way toward assuring that the

ASCI program is producing reliable and error-tolerant code. The

simulation included three-dimensional design features in the secondary and was compared to a nuclear test. An important step permitting high confidence in simulation was made when Los Alamos

was able to run a three-dimensional computation of energy flow. This

run took 18 days.

The structural performance and integrity of the B61 Mod 11

earth penetrator bomb were simulated on Blue Mountain in 23,000

separate runs to assess the reliability of the weapon over a wide

range of environmental parameters. The resulting statistical analysis was validated against a small number of actual drop tests. Simulation permitted the designers of this new weapon to have high confidence in its performance and saved a significant amount of time

and money by reducing the required number of destructive hardware tests.5

New Weapon Designs

For the 50-plus years of the nuclear age, it has been assumed

that no nuclear weapon would be accepted for serial production and

for inclusion in the U.S. stockpile without a full-scale test (aboveground before the Limited Test Ban Treaty of 1963, underground

since then). One of the developments that permitted the United

States to contemplate the total cessation of nuclear testing in the

post-Cold War era was the seeming lack of any need for new weapon

types or designs.

In the years since testing ended in 1992, the previous perception of many serving officers and national leaders that new weapons

were unnecessary has begun to change. For example, C. Paul Robinson, director of the Sandia National Laboratory, has suggested the need to

develop a low-yield earth-penetrating

weapon that would enable the United

States to hold at risk deeply buried command bunkers. A weapon of lower yield

than the present earth penetrator, the

B61 Mod 11, would be required to minimize collateral damage and fallout.

Deeper penetration than can be achieved

by the B61 Mod 11 would increase the

coupling of energy to the ground, thus

permitting the desired yield reduction. This probably would be an

example of a new nuclear weapon that could be designed, certified,

and produced entirely without a nuclear test, although most experts

outside the Departments of Defense and Energy doubt whether fallout can be contained or adequate penetration achieved; those analysts also think low-yield weapons may be insufficient to destroy a

hard and deeply buried target, and that any weapon with a yield that

can destroy the target will necessarily produce a great deal of fallout.

Since the late 1960s, the United States has pursued one general

type of nuclear weapon in many variants, ranging from low-yield battlefield weapons to high-yield designs suitable for attacking large

areas or hard near-surface targets. Because the United States has

studied this particular corner of design space in great detail for

many years, it has significant information about which ideas work

and which do not. The accuracy of new simulation computer programs can be tested against both this enormous database (comprising nearly 1,000 nuclear explosions) and the results of the legacy

codes used to design the devices that were already tested.

Designs similar to those used for nuclear artillery shells should

provide a baseline from which to produce plans for an earth-penetrating weapon in the low-kiloton yield range. An artillery-fired

atomic projectile (AFAP) is subjected to roughly the same acceleration forces on launch as an earth-penetrating weapon is on impact.

Consider the acceleration experienced by a 203-millimeter shell in a

4 Defense Horizons August 2002

structural performance

and integrity of the earth

penetrator bomb were

simulated over a wide

range of environmental

parameters
relatively conventional gun of 55 caliber6 and a 900-meter-per-second

muzzle velocity. If the force on the projectile is constant from firing

until it leaves the gun,7 then the average acceleration is 36,274

meters/second2, or 3,700 times the force of gravity. Lateral vibration

in the barrel is also likely to be severe but cannot be so simply estimated. If the same shell strikes the ground at its muzzle velocity

(neglecting air resistance) and is so strongly constructed that it penetrates 10 meters into the earth before coming to a halt, the deceleration force on the projectile is almost exactly equal to that experienced during firing. In general, the deeper a munition is intended to

penetrate the earth, the lower will be those decelerations because

the weapon travels a longer distance before coming to rest.

Thus, existing AFAP designs are reasonable surrogates for the

physics package needed in an earth penetrator. The performance of

the earth-penetrating B61 Mod 11, which used a new case and an

existing physics package, was computer simulated on machines considerably slower and less powerful than those available today.

If national decisionmakers commission a new earth-penetrating nuclear weapon, it should be possible to design and certify it

without nuclear yield testing by using a procedure much like the

following:

■ Select an AFAP design comparable in size and yield to the military

characteristics of the desired final weapon

■ Modify the nuclear design in the smallest possible ways using ASCI

simulation until the new weapon is considered able to withstand the decelerations expected on impact

■ Design an appropriate case for the weapon, including whatever kind

of penetrating nose is appropriate using the structural design codes made

possible by the new generation of computers

■ Test the implosion properties of the new primary (with simulants

substituted for the nuclear materials) using existing or newer facilities,

such as DAHRT, to ensure that the weapon functions properly before impact

■ Drop test8 an identical device in its casing; extract the physics

package from the rubble; and then detonate the high explosives at DAHRT.

The detonation system would not be live during the drop-test part of this

experiment.

■ After verifying that the physics package survives impact and performs properly, drop test another simulated device to verify that its high

explosive detonates at the appropriate depth and velocity.

This procedure differs very little from what would be done if

nuclear testing were allowed. Because the Limited Test Ban Treaty

prohibits venting radioactive debris from a nuclear test to the atmosphere, a full-up test of the system would not be possible. The survival

of a real physics package and its proper functioning after impact

would, in any case, have to be inferred from the survival and functioning of a nonnuclear replica. In turn, the functioning of the

replica would be checked at a hydrodynamic facility in the same way

as suggested above.

General Considerations

Many of the difficult experiments involved in qualifying a new

weapon based on an existing device design are nonnuclear and

involve such issues as mechanical and electrical integrity and functioning after passing through a severe environment. Since none of

these experiments would involve actual functioning nuclear components, they may be performed under all interpretations of the CTBT.

If new weapons designs are to be produced and certified without a nuclear test, they ought to resemble closely designs already

tested. In particular, the shapes of the nuclear components and

internal systems such as boost-gas piping, the type of high explosive used, and its geometry should be quite close to the tested

designs, with the excursions well understood on the basis of both

ASCI and legacy codes. Any new design should be conservative, not

attempting to achieve reductions in size, amount of high explosive,

and special materials. Additional plutonium or a different mixture

of boost gas can convert a “prima donna” design into one that is

more rugged and in which the designers can have more confidence. 

An increase in plutonium or highly enriched uranium might

reduce the safety margin of the device, while an increase in tritium

in the boost gas could decrease the primary yield needed to initiate

boosting. All of these tradeoffs seem possible, and the ASCI simulation capability gives designers their first opportunity to investigate

the performance of a new weapon without first exploding it. Nevertheless, new weapon designs will likely resemble closely the designs

of older weapons and come from the regions of design space where

the United States has considerable experience, as they did when

testing was allowed.

Notes1 megaOPS: million computer operations per second; gigaOPS: billion computer

operations per second; teraOPS: trillions of computer operations per second. An operation, for example, is the addition of two numbers.

2 terabyte: one trillion bytes. For comparison, the Department of Energy and

others estimate that all the material in the Library of Congress together amounts to

about one terabyte. 3 Mix is the mixing of the inner lining of the hollow pit of a primary with the deuterium-tritium mixture, which causes boosting. 4 For comparison, the computer on which this paper is being written is capable

of several hundred megaOPS, has a 1 GHz clock speed, and contains 512 megabytes of

random access memory, along with a 40 GByte hard drive. This is comparable to the

capability of the Cray supercomputer on which the WB88 warhead was designed. 5 Data on specific simulations taken from the unclassified fiscal year 2001 ASCI

program plan, DOE/DP/ASCB2001BASCIBProgB001. 6 55 caliber denotes that the length of the gun barrel is 55 times the diameter of

the projectile, or in this case is 11.2 meters long. 7 This is a reasonable assumption, although it is certainly not strictly true. However, it does provide a reliable figure for the average acceleration. 8 Or, to achieve a higher impact velocity, one could accelerate the device electrically or with an attached rocket.

August 2002 Defense Horizons 5

Defense Horizons is published by the Center for Technology and National Security Policy through the

Publication Directorate of the Institute for National Strategic Studies, National Defense University.

Defense Horizons and other National Defense University publications are available online at

http://www.ndu.edu/inss/press/nduphp.html.

The opinions, conclusions, and recommendations expressed or implied within are those of the

contributors and do not necessarily reflect the views of the Department of Defense or any other

department or agency of the Federal Government.

Center for Technology and National Security Policy

Hans Binnendijk

Director
6 Defense Horizons August 2002

The DefenseHorizons Series

Number 1, June 2001

Managing Change: Capability,

Adaptability, and Transformation

Hans Binnendijk and Richard L. Kugler

Number 2, September 2001

Resurrecting Transformation for the 

Post-Industrial Era

Douglas A. Macgregor

Number 3, October 2001

UCAV Technological, Policy, and

Operational Challenges

Charles L. Barry and Elihu Zimet

Number 4, October 2001

Maritime Access: Do Defenders Hold 

All the Cards?

Arthur H. Barber III and Delwyn L. Gilmore

Number 5, November 2001

Adapting Forces to a New Era: Ten

Transforming Concepts

Hans Binnendijk and Richard L. Kugler

Number 6, December 2001

Current Export Policies: Trick or Treat?

David R. Oliver, Jr.

Number 7, February 2002

Global Trade: America’s Achilles’ Heel

James M. Loy and Robert G. Ross

Number 8, February 2002

Small Security: Nanotechnology and

Future Defense

John L. Petersen and Dennis M. Egan

Number 9, March 2002

Nonlethal Capabilities: Realizing 

the Opportunities

E.R. Bedard

Number 10, March 2002

Rediscovering the Infantry in a Time 

of Transformation

Bing West

Number 11, April 2002

Computer Games and the Military: 

Two Views

J.C. Herz and Michael R. Macedonia

Number 12, April 2002

The Airborne Laser from Theory 

to Reality: An Insider’s Account

Hans Mark

Number 13, May 2002

Relevancy and Risk: The U.S. Army and

Future Combat Systems

Joseph N. Mait and Jon G. Grossman

Number 14, June 2002

Toward Missile Defenses from the Sea

Hans Binnendijk and George Stewart

Number 15, July 2002

Biological Weapons: Toward a Threat

Reduction Strategy

Brad Roberts and Michael Moodie

Number 16, August 2002

The Virtual Border: Countering 

Seaborne Container Terrorism

Hans Binnendijk, Leigh C. Caraher, Timothy Coffey,

and H. Scott Wynfield