Contacts: Daryl Kimball, Executive Director; (202) 463-8270 x107; Kelsey Davenport, Director of Nonproliferation Policy, (202) 463-8270 x102; Kingston Reif, Director of Disarmament and Threat Reduction Policy, (202) 463-8270
Updated: April 2017
In the April 2010 Nuclear Posture Review (NPR), the United States declared that it would not use nuclear weapons against non-nuclear-weapon states that are members in good standing of the nuclear Nonproliferation Treaty (NPT). Previously, successive administrations had maintained a policy of "strategic ambiguity" by refusing to rule out the use of nuclear weapons in response to biological or chemical weapons attacks, even from NPT member states.
The 2010 NPR states that the
The 2010 NPR updates earlier versions of U.S. "negative security assurances" first enunciated in 1978 and reaffirmed in 1995: "The United States reaffirms that it will not use nuclear weapons against non-nuclear-weapon States Parties to the Treaty on the Non-Proliferation of Nuclear Weapons except in the case of an invasion or any other attack on the United States, its territories, its armed forces or other troops, its allies, or on a State towards which it has a security commitment, carried out or sustained by such a non-nuclear-weapon State in association or alliance with a nuclear-weapon State."
The 1995 formulation left open the option to use or threaten to use nuclear weapons against non-nuclear-weapon states that were “in association or alliance with” a nuclear-weapon state—generally understood to be a reference to the Warsaw Pact allies of the Soviet Union. The United States also specified at that time that non-nuclear-weapon states had to be in compliance with the NPT to be eligible for this assurance.
In 1995, UN Security Council Resolution 984 recognized the U.S. assurances and similar ones from Russia, China, France and the United Kingdom. These coordinated assurances were a key part of the multilateral decision to indefinitely extend the NPT that year.
Outside of the NPT context, however, senior U.S. officials maintained "strategic ambiguity" about Washington’s military options in key situations. For example, just before the U.S. war with Iraq in 1991, former Secretary of State James Baker told Tariq Aziz, Iraq's foreign minister, that if "you use chemical or biological weapons against U.S. forces, the American people will demand vengeance and we have the means to exact it." Baker said that "it is entirely possible and even likely, in my opinion, that Iraq did not use its chemical weapons against our forces because of that warning. Of course, that warning was broad enough to include the use of all types of weapons that American possessed."
Similarly, in April 1996, in reference to a suspected Libyan chemical weapons facility at Tarhunah, then-Secretary of Defense William Perry said that "if some nation were to attack the United States with chemical weapons, then they would have to fear the consequences of a response from any weapon in our inventory." Perry noted that "in every situation that I have seen so far, nuclear weapons would not be required for response."
The previous NPR in 2001 maintained the possibility that U.S. nuclear forces could be used against non-nuclear nations. In addition to nuclear-armed China, the 2001 NPR cited five states that at the time did not have nuclear weapons (Iran, Iraq, Libya, North Korea and Syria) as driving "requirements for nuclear strike capabilities." All five states were at the time suspected of nuclear weapons ambitions and were believed to have biological and/or chemical weapons or programs. In February 2002, then-State Department spokesman Richard Boucher said it was U.S. policy that "[i]f a weapon of mass destruction is used against the United States or its allies, we will not rule out any specific type of military response."
In September 2002, the classified National Security Presidential Directive 17 was signed, which stated that "the United States will continue to make clear that it reserves the right to respond with overwhelming force--including potentially nuclear weapons--to the use of WMD against the United States, our forces abroad, and friends and allies."
In an April 6, 2010 statement, President Barack Obama said the
As Secretary of Defense Robert Gates explained in an interview broadcast April 11 on CBS’s Face the Nation, negative security assurances are “not a new thing. The new part of this is saying that we would not use nuclear weapons against a non-nuclear state that attacked us with chemical and biological weapons.”
As for chemical weapons, Gates said April 11 that “[T]ry as we might, we could not find a credible scenario where a chemical weapon could have the kind of consequences that would warrant a nuclear response.” On biological weapons, the 2010 NPR hedges: “Given the catastrophic potential of biological weapons and the rapid pace of bio-technology development, the United States reserves the right to make any adjustment in the assurance that may be warranted by the evolution and proliferation of the biological weapons threat and U.S. capacities to counter that threat.”
For both scenarios, Gates said April 6 that “[i]f any state eligible for this assurance were to use chemical or biological weapons against the United States or its allies or partners, it would face the prospect of a devastating conventional military response.” And for states that have nuclear weapons or are not in compliance with the NPT, such as North Korea and Iran, all options are on the table—including the use of nuclear weapons first or in response to a non-nuclear attack.
The NPR notes, however, that the United States would only consider the use of nuclear weapons in “extreme circumstances to defend the vital interests of the United States or its allies and partners.” As Gates put it in his April 6 remarks, nuclear weapons are “obviously a weapon of last resort.”
Under the NPT, the five recognized nuclear-weapon states are China, France, Russia, the United Kingdom, and the United States. Three other states, India, Pakistan, and Israel, possess nuclear weapons but never joined the NPT. In addition, three NPT members are not in compliance: North Korea has tested nuclear weapons and disavows its nonproliferation obligations, Iran has been found in noncompliance by the International Atomic Energy Agency (IAEA), and Syria is under investigation for its potential violations.
For states not covered by U.S. negative security assurances, the NPR foresees “a narrow range of contingencies” in which the
Although the 2010 NPR states that the “fundamental role” of
The Trump administration began its Nuclear Posture Review in April 2017. It is expected to be completed by early 2018.