Key P-5 Public Statements on CTBT Scope

Fact Sheet
Bureau of Arms Control, Verification, and Compliance

U.S. Statements on CTBT Scope

“The treaty does not contain our proposal that the treaty’s scope provide room for so-called “hydronuclear” experiments with very small nuclear yields.”

Former U.S. ACDA Director John Holum
Conference on Disarmament Plenary, August 1996

“I have heard some critics of the Treaty seek to cast doubt on whether Russia …committed itself … to a truly comprehensive prohibition of any nuclear explosion, including an explosion…of even the slightest nuclear yield. In other words, did Russia agree that hydronuclear experiments, which do produce a nuclear yield, although usually very, very slight, would be banned and that hydrodynamic explosions, which have no yield because they do not reach criticality, would not be banned? The answer is a categorical ‘yes.’ The Russians as well as the rest of the P-5 did commit themselves.”

Ambassador Stephen Ledogar, Chief U.S. Negotiator of the CTBT
October 7, 1999

Russian Statements on CTBT Scope

“[A]ll [of the G-8], to the very last one, agreed that this year we’ve got to sign the treaty on banning testing in any size forever and forever.”

Russian President Boris Yeltsin
Joint Press Conference with U.S. President Bill Clinton, April 21, 1996

“We are prepared to sign today a ban on nuclear weapon tests in any environment starting with this year, and on tests of any magnitude.”

Russian President Boris Yeltsin
Joint Press Conference with French President Jacques Chirac, April 20, 1996

“The CTBT should be universal, unlimited, nondiscriminatory, and without threshold values.”

Russian Ambassador Grigory Berdennikov
Conference on Disarmament Plenary, March 7, 1996

“I would like to remind you that the Russian delegation has always argued that this treaty should contain no threshold restrictions whatsoever. We note with satisfaction that this approach is now shared by other participants in the negotiations.” Russia accepted that any nuclear weapons-test explosion or any other nuclear explosion in any environment will be banned forever and without any thresholds.”

Russian Ambassador Grigory Berdennikov
Conference on Disarmament Plenary, May 14, 1996

“Qualitative modernization of nuclear weapons is only possible with the conduction of actual and hydronuclear tests with any fission yield that contradicts the CTBT directly.”

Yuri Kapralov, Russian Ministry of Foreign Affairs
During Ratification Debate, January 2000

“Russia, from the very beginning, was supporting the proposal of a nuclear explosion ban without thresholds….The difficult negotiations resulted in a compromise. On the one hand, the Treaty prohibits any nuclear explosion, however low the yield, and on the other hand, it permits experiments with nuclear weapons, including those of the explosive nature, but under the condition that they are purely chemical (the so called ‘hydrodynamic experiments’).

Ambassador Grigory Berdennikov
December 7, 2005

“Under the global ban on nuclear tests, we can only use computer-assisted simulations to ensure the reliability of Russia’s nuclear deterrent.”

Russian President Dmitry Medvedev
July 29, 2009

British Statements on CTBT Scope

“I wish now to put on record my government’s position that the CTBT should not permit any nuclear weapon test explosion involving any release of nuclear energy, no matter how small.”

UK Ambassador Weston
Conference on Disarmament Plenary, September 14, 1995

“There was agreed at this summit a new impetus to the conclusion…of a Comprehensive Test Ban Treaty which bars all nuclear explosions on the basis of a zero yield. And I know from time to time in the past there have been conflicting interpretations of what is meant by zero yield. Let me make it clear that what we mean by this, is that no nuclear explosion of any kind, however small, is permitted.”

British Prime Minister John Major
April 20, 1996

“Sub-critical tests are not prohibited by the treaty.”

Tony Lloyd, Minister of State, Foreign and Commonwealth Office
During Ratification Debate, November 1997

“…(W)e recognize, as does the treaty, that sub-critical experiments are consistent with the treaty.”

Tony Lloyd, Minister of State, Foreign and Commonwealth Office
During Ratification Debate, March 1998

Chinese Statement on CTBT Scope

“China is committed to concluding a CTBT which prohibits any nuclear-weapon test explosion at any place and in any environment. Proceeding from this guiding principle, the Chinese delegation proposed at the outset of the negotiations its scope text prohibiting any nuclear-weapon test explosion which releases nuclear energy. The phrase ‘release of nuclear energy’ was intended to distinguish the scope of the CTBT from that of the PTBT and TTBT and to define the scope of the CTBT with more precise and scientific language. The Chinese delegation has always held that the scope of the CTBT should exclude any threshold. After two years of negotiations, most countries have reached a common understanding on the phrase “any nuclear-weapon test explosion” in the scope article. That is to say, the future CTBT will without any threshold prohibit any nuclear-weapon test explosion.”

Chinese Ambassador Sha Zukang
Conference on Disarmament Plenary, March 28, 1996

French Statements on CTBT Scope

France supported a total ban on nuclear tests “at whatever level.”

The French Elysee
August 16, 1995

“…the very general scope of the prohibition imposed by the treaty, since it covers all nuclear explosions, regardless of their power…This is the consecration of the “zero option…Experiments that do not involve the release of nuclear energy including what experts call ‘cold tests’ remain allowed.”

Pierre Moscovici, Minister Delegate for European Affairs
During Ratification Debate, March 25, 1998

“The Treaty prohibits, in effect, all nuclear tests regardless of their conditions of achievement and power…It maintains the possibility of testing called ‘cold” tests and ‘subcritical’, no nuclear chain reaction.”

Serge Vincon, former Vice President of the French Senate
During Ratification Debate, March 25, 1998

“In proposing August 10, 1995 to dedicate the “zero option,” that is to say a complete ban on all nuclear explosions regardless of the level, France has greatly contributed to unblock the negotiations...”

“At one time supported by some nuclear countries, the possibility of testing low power (hydro-testing) was finally dismissed, especially as discussions on the remaining level of energy released, which could be considered acceptable.”…(T)he Comprehensive Test Ban Treaty (CTBT), which prohibits the use of nuclear tests in full scale, including those of low energy…”

Yannick D’Escatha, Director General of the Commissariat a l’Energie Atomique
During Ratification Debate
French Senate Foreign Affairs Defense and Armed Forces Commission, Report no 330, 1997-1998


Explanatory Note on Terminology

Over the course of the multi-year CTBT negotiations, there were significant discussions about the scope of the Treaty, or what exactly would be prohibited.  Some parties proposed initially that nuclear explosive tests below some small yield—or “threshold”—should be allowed. Ultimately a low threshold test ban was rejected. By the end of the negotiations, all parties understood that the CTBT should be a true “zero yield” treaty; nuclear weapon test explosions that produce any level of nuclear yield are prohibited.

Some countries prefer to use the term “no threshold,” meaning there is no line (or threshold) below which any amount of yield from a nuclear weapon test explosion would be allowed, and this usage is reflected in statements by senior P 5 government officials. The expression is translated into English in various ways: prohibition of “tests at whatever level,” “without any threshold,” “without threshold values,” “regardless of the power,” “any release of nuclear energy,” or “regardless of the level”.  All of these formulations refer to the same concept: zero yield.