Letter to Congress: Scientists Urge U.S. to Remain Party to Iran Nuclear Deal

October 30, 2017

Weapon Program: 

  • Nuclear
  • Missile

Senator Bob Corker, Chairman, Senate Foreign Relations Committee
Senator Ben Cardin, Ranking Member, Senate Foreign Relations Committee Representative
Ed Royce, Chairman, House Foreign Affairs Committee Representative
Eliot Engel, Ranking Member, House Foreign Affairs Committee

Dear Senators Corker and Cardin, and Representatives Royce and Engel,

The United States Congress has momentous responsibilities with regard to the nuclear agreement with Iran. As scientists who understand the physics and technology of nuclear power, of nuclear explosives, and of long-range missiles; and who collectively bring experience with nuclear nonproliferation, we would like to provide you with our perspective on the wisest path forward. 

Recent statements by the United Kingdom, France, Germany, the European Union, and Iran make clear that renegotiation of the Joint Comprehensive Plan of Action (JCPoA) is an unrealistic objective. Since the JCPoA imposes strict restrictions and strong verification on Iran’s nuclear program, Congress should act to ensure that the United States remains a party to the agreement. Along with assuring the continuation of the agreement, this will allow the United States to influence its implementation, including inspections at military installations, through its position on the Joint Commission.

The JCPoA does not cover non-nuclear activities by Iran; any such issues could be addressed separately. For example, recent reports suggest that Iran might be open to mutually respectful negotiations addressing limits to Iran’s missile program. We encourage you to recommend that the United States pursue this potential opportunity.

President Trump has expressed concerns about the long-term implications of the JCPoA for Iran’s nuclear program. The severe restrictions on Iran’s stockpile of low-enriched uranium remain in place through 2030, and continuous surveillance of Iran’s centrifuge production through 2035. Surveillance of uranium mines and mills remains through 2040. Thereafter, Iran returns fully to International Atomic Energy Agency (IAEA) safeguards under the “Additional Protocol,” the strongest set of generally applicable safeguards implemented by the IAEA. In contrast, during most of its prior history, Iran’s nuclear program was subject only to the minimum level of IAEA safeguards.

There are additional measures that would make it more difficult for any country with enrichment facilities to produce secretly material for weapons. First, it would be valuable to have stronger verification procedures at uranium enrichment plants worldwide. In particular, the IAEA should implement real-time verification at large-scale uranium enrichment plants in non-nuclear weapon states where the IAEA is unable to reach a “Broader Conclusion” of the absence of undeclared nuclear materials and activities.

Second, multi-national control of uranium enrichment plants—such as a strengthened version of the arrangements within the European company URENCO—could provide an extra layer of security against their misuse to produce material for nuclear weapons, due to oversight by officials of multiple nationalities. Congress should recommend that the Executive Branch, in collaboration with all other member states of the IAEA and the IAEA itself, work to strengthen uranium enrichment plant safeguards worldwide, and implement multi-national control of uranium enrichment capabilities. Continuation of the JCPoA is necessary to provide the time needed to develop and implement these initiatives.

We hope that you will take into account the perspectives presented here. We stand ready to discuss these matters in more detail with you at your request.


Richard L. Garwin
Member of the National Academies of Sciences, Engineering and Medicine
National Medal of Science (2002)
Presidential Medal of Freedom (2016)

Robert J. Goldston
Professor, Astrophysical Sciences, Princeton University

Rush Holt
Chief Executive Officer, American Association for the Advancement of Science

R. Scott Kemp
Associate Professor, Nuclear Science and Engineering, MIT
Director, MIT Laboratory for Nuclear Security and Policy

Frank von Hippel
Senior Research Physicist and Professor of Public and International Affairs, Emeritus, Princeton University

View the letter and a full list of signatories below.