Statement byRichard Garwin, Council on Foreign Relations, Prepared for the Senate Foreign Relations Committee Hearing on the CTBT

October 7, 1999


Good afternoon. Thank you for the opportunity to testify in support of the Comprehensive Test Ban Treaty.

I am Richard L. Garwin, Philip D. Reed Senior Fellow for Science and Technology at the Council on Foreign Relations. I am also IBM Fellow Emeritus at the Thomas J. Watson Research Center of the IBM Corporation. I chair the Arms Control and Nonproliferation Advisory Board to the Secretary of State. In addition, I am a member of the JASON group of consultants to the US government, and have participated in several of the JASON studies for the Department of Energy on stockpile stewardship. Since 1950 I have been involved with the nation's nuclear weapons establishment, having contributed to the development and testing of fission weapons and to the creation of the first thermonuclear weapons. Most of this involvement has been at the Los Alamos national Laboratory. I am currently a consultant to Sandia National Laboratories. Nevertheless, in my testimony I speak only for myself. In 1998 I was a member of the Rumsfeld Commission to Assess the Ballistic Missile Threat to the United States. In 1996 1 received from the US foreign intelligence community the R.V. Jones Award for Scientific Intelligence; and also in 1996 I received from the President and the Department of Energy the Enrico Fermi Award for my work with nuclear weapons.

The bottom line.

Complex technical issues should not be allowed to obscure the important conclusions that I state here, up front, and that I believe follow from a balanced assessment:

1. In assessing the merits of the CTBT it is essential to bear the difference in mind between fission weapons of the Hiroshima-Nagasaki variety and thermonuclear weapons which are used on all deployed US, Russian and Chinese strategic nuclear weapons.

2. The CTBT can be verified with sufficient confidence to prevent any proliferator from developing thermonuclear weapons whether he already possesses fission weapons or develops such weapons clandestinely.

3. While tests with yields vastly smaller than Hiroshima may evade detection, such tests would be useless to Russia and China, and very difficult to use for confirming the validity of a clandestinely developed fission weapon.

4. If secret information regarding thermonuclear weapons has been acquired by others, or may be so acquired in the future, as has been alleged in regard to China, this information cannot be turned into a deployable weapon without tests forbidden by the CTBT.

5. The US does not need tests banned by the CTBT to maintain full confidence in its weapons stockpile. The vast majority of components in a nuclear weapon can be examined and tested and upgraded without nuclear explosions. The nuclear (or physics) package itself can be remanufactured to original specifications should surveillance reveal deterioration. The stockpile stewardship program will further enhance our high confidence in our stockpile, which is now certified each year by the weapon builders, together with the military who will have to use the weapons.

6. Given that nuclear proliferation is probably the most serious threat to the national security, and given the confidence that our own deterrent will be fully maintained under the CTBT, it is clear -- totally clear -- that the United States will run fewer dangers with the CTBT in force than without it.PAGE 2 WHY A TREATY?

We are better off with a test ban than without it. Of that there can be no doubt.

Naturally, any treaty or contract will have both benefits and costs to any of the parties. Here we are concerned with the benefits and costs to the United States. If one looked only at the costs, and imagined them as the total effect of the Treaty, one would never consider such a deal.

The costs to the United States include constraining the United States from testing nuclear weapons. The benefits come from constraining other countries from testing nuclear weapons. So let's look first at the benefits. The greatest benefit of the CTBT arises from its contribution to preventing the proliferation of nuclear weapons. It does this directly by preventing nuclear tests and indirectly by keeping nations on board the Nonproliferation Treaty (NPT). The United States does not want additional states to have nuclear weapons, and the members of the NPT don't either.

It is possible to build simple nuclear weapons without nuclear explosion tests, but there will always be a nagging doubt whether or how well they will perform. The Hiroshima and Nagasaki bombs each weighed about 9000 pounds, with a yield of 15 to 20 kilotons. The Hiroshima bomb used artillery-gun assembly of 60 kilograms of enriched uranium, which was not tested before its use. The Nagasaki bomb, tested three weeks beforehand in the New Mexico desert, contained some 6 kilograms of plutonium. Compare these weapons with a two-stage thermonuclear bomb tested in 1957 that weighed some 400 Ihs with a yield of 74 kilotons; its diameter was a mere 12 inches, with a length of some 42 inches.

Without nuclear tests of substantial yield, it is difficult to build compact and light fission weapons and essentially impossible to have any confidence in a large-yield two-stage thermonuclear weapon or hydrogen bomb, which can readily be made in the megaton class. Furthermore, even in the yield range accessible to fission weapons, thermonuclear weapons are attractive because of their economy of fissile material, their compact size, and their improved safety. Just for example, a pure fission weapon, which is the best a sophisticated proliferator could do without verifiable testing, of 200 kilotons yield would require some 60 kg of plutonium or U-235. And the chemical explosive might weigh 4000 to 8000 lbs. That amount of fissile material would suffice for 10 thermonuclear weapons, each of which could be in the megaton class and weigh less than 1000 lbs. However, such H-bomb type weapons would require testing that would be readily detected and would therefore be prevented by the CTBT. This limits greatly the destructive power that can be wielded by newly nuclear states such as India and Pakistan.

So a CTBT that was respected would make a big difference in the threat that could face the United States or our allies, even if nations overtly or clandestinely pursue nuclear weaponry without explosive tests.

The CTBT bans any nuclear explosion of any size-- it is a "zero threshold" agreement.

Can one be certain that a nation has not tested in the vast range between zero and the magnitude of test that would be required to gain significant confidence in an approach to thermonuclear weaponry-- say, 10 kilotons? No, but the utility of such tests to a weapons program has been thoroughly explored and found to be minimal.

First, I recall the August 3, 1995 report of JASON chaired by Dr. Sidney Drell, of which I was a co-author. Conclusion 6 of that study refers to a nuclear weapon test that would involve full yield of the fission primary and some ignition of the thermonuclear secondary, and that such tests, to be useful, would "generate nuclear yields in excess of approximately 10 kilotons." That is clearly verifiable by the CTBT's International Monitoring System (IMS), with its seismic, hydroacoustic, and infrasound sensors, and its detectors of radioactive gases and particles.

These Conclusions resulted from a detailed classified analysis of the more than 1000 nuclear tests, and they were supported unanimously by the authors of the study, including four experienced nuclear weapon designers from US nuclear weapon laboratories.

A proliferant country might well want to acquire fission weapons of 5 kiloton yield, but the chance of detonating such a weapon undetected is small. The International Monitoring System (IMS) will have a good probability of detecting a nuclear explosion anywhere in the world-- underground, underwater, or in the atmosphere at a level of 1 kiloton. And in many portions of the world the detectability is much better. For example, on September 23, 1999, the background noise in seismic arrays in the Scandinavian region was such that a test on the order of 1 ton (not 1 kiloton) could have been detected at Novaya Zemlya.

The CTBT bans explosive tests that release any amount of nuclear energy. The United States conducted some scores of so-called hydronuclear tests with an intended energy release less than 4 lbs. of high explosive equivalent. These are banned under the CTBT; they would very likely not be detected by the International Monitoring System. It is clearly impossible seismically to distinguish a test that may have had 200 lbs of high explosive from a test with 200 lbs of high explosive and 1 lb of nuclear yield. The 1995 JASON Nuclear Testing study judged that there was little to be learned from such a test of yield 10 million times lower than that of the bombs that destroyed Hiroshima and Nagasaki. Such major changes would need to be made in a full-scale nuclear explosive to produce such a small yield that information available from the hydronuclear test would be of minor value in the development of a substantial fission weapon.

Russian nuclear weapons experts have expressed interest in fission weapons with yields no bigger than a few tons. These might be built without testing, or might be tested unobserved by US sensors, with or without a CTBT. In no case would the US react by testing its own nuclear weapons, and the inhibition posed by a CTBT on a Russia that wishes to remain engaged with the rest of the world would be substantial. The possibility of Russian programs of this type is not a valid argument against the CTBT.

In other words, one can cheat on the CTBT without being discovered by the International Monitoring System, but to what end? Useful national security information would not be acquired, and the bragging rights are not worth much if one can't tell anyone. For instance, a clandestine test cannot be used to intimidate other states.


In addition to the International Monitoring System, the United States will maintain national means ranging from human agents to communications intelligence to sensors other than those included in the IMS. Furthermore, there are completely open and unclassified sensors such as research seismometers that can augment and in many cases greatly improve the sensitivity of the IMS.

I am confident that the CTBT can be adequately verified; this means that experimental validation by nuclear explosion testing cannot be accomplished by a state that is party to the CTBT.


Our review of the US nuclear tests and of defects discovered in stockpile weapons revealed many defects that were detected in the routine surveillance process-- i.e., not by nuclear explosion tests. Defects observed by nuclear explosion tests were associated with weapons that had been put into the stockpile without the normal development testing and a production verification test. Today we have no such weapons; and we will have none in the future. All weapons in the enduring stockpile have been fully tested.

Some deficiencies identified by surveillance were eliminated by substituting a different warhead or design that required nuclear testing, but that was an option-- not a necessity.

This analysis of our own stockpile and test record underscores the importance of explosive testing at an assuredly detectable level to a proliferator.

At present and for the foreseeable future, a reliable and safe US nuclear weapons stockpile is essential to the security of the United States, its allies, and to peaceful nations of the world. It is important to understand whether US nuclear weapons can be maintained reliable and safe for 10 years or 20 years or 50 years, without nuclear testing. To this end, the Department of Energy is spending $4.5 billion annually on the Stockpile Stewardship Program, to provide assessment and understanding of the state of the stockpile and to remedy deficiencies as they are detected. Of the 4000 or so individual parts of a modem US nuclear weapon, most can be thoroughly tested without nuclear explosions and many are not even involved in a test explosion. Thus, batteries, timing and fuzing systems, and most of the weapon itself can be assessed and improved to the state-of-the-art, using modem technology when it is warranted by the reduction in cost in the long run to compensate the investment in the short run. This is no different from any other modernization program. But under a CTBT, the explosive-driven plutonium primary cannot be tested to nuclear yield, and neither can the secondary explosive that is ignited by the flood of x rays from the primary explosion.

Instead, the United States has an assessment program, in which each year 11 examples of each type of warhead in the inventory are dismantled and exhaustively monitored. Of the 11, one is totally disassembled and the interior of the primary and secondary inspected for aging, corrosion, and the like.

Eventually, signs of aging may force the remanufacture of these parts; if they are remanufactured to the same specifications as they were initially produced, they will be as good as the day they were first made. This can be done any number of times, and is the basis for my confidence in the future stockpile. As a result of the Stockpile Stewardship Program over the last four years or so, we have a much better understanding of the aging of plutonium than we did previously. It seems to be benign, and this knowledge has led to a belief that the plutonium pit will survive for 50 years or more. But if it doesn't, remanufacture will make it "good as new".

We need to have not only the assessment but the remanufacturing facility; the need for that facility has nothing to do with the CTBT. It is neither more nor less necessary under a CTBT than in a regime in which the United States might still test occasionally.

The US laboratories under the CTBT will maintain weapons safe and reliable by the Stockpile Stewardship Program, but they will also maintain and improve the capability to design and build nuclear weapons. It is clear that this capability could not be exercised under a CTBT in the form of newly produced weapons, but should the CTBT regime ever collapse, it would avoid a delay of many years before new- design nuclear weapons could be produced.


The nonproliferation and arms control benefits to the US of a CTBT are substantial; the adherence of other nations to the Nonproliferation Treaty and to the CTBT is fundamentally influenced by US ratification of the CTBT. A Party could conduct tiny nuclear tests without being detected by the Treaty's monitoring system, but tests in the hydronuclear range releasing a millionth of the energy of a Hiroshima bomb will provide little useful knowledge; tests releasing 100 tons-- that is, 1% of the Hiroshima yield-might sometimes be missed by the monitoring system, but would often be detected and located by other means. They, too, would have little value in the development of nuclear weapons. US nuclear weapons will be maintained reliable and safe under a CTBT, thanks to the Stockpile Stewardship programs for assessment and remanufacture. Last but not least among the six safeguards that the Administration has announced is the explicit readiness to invoke the supreme national interest clause should the need arise as a result of unanticipated technical problems in the enduring stockpile of nuclear weapons, that affect a key portion of that stockpile.

On the basis of my experience in the nuclear weapons program, I agree with those US military leaders who have reviewed the benefits and costs to US security from a CTBT and strongly support the Treaty. Our national security will be improved by ratification and impaired by further delay.

It is thus greatly in our interest to ratify the CTBT now.