[Table of Contents][Go Back to Previous][Advance to Next][Bottom of Page]

Chapter 5

The United States’ nuclear forces and posture were carefully examined during the Quadrennial Defense Review (QDR). In evaluating the current and projected security environment, the QDR concluded that nuclear forces remain an important disincentive to nuclear, biological, and chemical proliferation and a hedge against the uncertain futures of existing nuclear powers, as well as a means of upholding U.S. security commitments to allies.

The QDR’s work was an important input to a Presidential Decision Directive issued in November 1997. The directive describes in general terms the purposes of U.S. nuclear weapons and provides broad guidance for developing operational plans. This is the first change in Presidential guidance for nuclear weapons employment since 1981, although operational plans have been updated regularly since then with commensurate reductions in the national target list.

The new directive notes that nuclear weapons play a smaller role in the U.S. security posture today than they have at any point during the second half of the 20th century, but that nuclear weapons are still needed as a hedge against an uncertain future, as a guarantee of U.S. security commitments to allies, and as a disincentive to those who would contemplate developing or otherwise acquiring their own nuclear weapons. Accordingly, the United States will maintain survivable strategic nuclear forces of sufficient size and diversity to deter any hostile foreign leadership with access to nuclear weapons.

The new directive provides a large measure of continuity with previous nuclear weapons employment guidance, including in particular the following three principles:

Deterrence is predicated on ensuring that potential adversaries accept that any use of nuclear weapons against the United States or its allies would not succeed.

A wide range of nuclear retaliatory options will continue to be planned to ensure the United States is not left with an all-or-nothing response.

The United States will not rely on a launch- on-warning nuclear retaliation strategy (although an adversary could never be sure the United States would not launch a counterattack before the adversary’s nuclear weapons arrived).

The United States is confident that it can maintain the deterrent called for in the new Presidential directive at the levels envisioned for a future Strategic Arms Reduction Treaty (START III) as agreed to in the March 1997 Helsinki Accords.


The START I treaty entered into force on December 5, 1994. Russia and the United States are working to achieve the final phase of nuclear force reductions mandated by that treaty by December 5, 2001 (see Table 11). The Treaty on Further Reduction and Limitation of Strategic Offensive Arms (START II) was approved by the U.S. Senate in January 1996 but has not yet entered into force, pending ratification by Russia. START II calls for further reductions in aggregate force levels, the elimination of multiple-warhead intercontinental ballistic missile (ICBM) launchers, the elimination of heavy ICBMs, and a limit on the number of submarine-launched ballistic missile (SLBM) warheads. The original START II treaty called for the final reduction phase to be completed no later than January 1, 2003.

At the conclusion of their March 1997 Helsinki meeting, President Clinton and Russian President Yeltsin issued a joint statement establishing parameters for future reductions in nuclear forces. The statement expressed the two leaders’ intent to begin START III negotiations immediately upon START II’s entry into force and to extend the deadline for elimination of strategic nuclear delivery vehicles under START II to December 31, 2007. The START III negotiations would consider further reductions in strategic nuclear warheads to an aggregate limit of 2,000-2,500 per nation by December 31, 2007.

To facilitate Russia’s ratification of the START II treaty, U.S. Secretary of State Albright and Russian Foreign Minister Primakov signed a Joint Agreed Statement and a Protocol to the Treaty in New York in September 1997, extending the time period for implementation of START II until December 31, 2007. In addition, Secretary Albright and Foreign Minister Primakov signed and exchanged letters legally codifying the Helsinki Summit commitment to deactivate, by December 31, 2003, the U.S. and Russian strategic nuclear delivery vehicles that under START II will be eliminated. START II’s entry into force will require Senate approval of the Protocol to the START II Treaty and its associated Joint Agreed Statement.

Since the establishment of the Cooperative Threat Reduction (CTR) program in 1991, the United States has been assisting Russia, Ukraine, Belarus, and Kazakhstan in implementing the nuclear force reductions required under the START I treaty. In anticipation of further reductions that would be mandated by the START II and III treaties, the United States has begun discussing with Russia additional CTR projects that would assist in accomplishing those reductions.

In the absence of a START II entry into force, the Department of Defense is taking steps to protect the option of maintaining a START I force level through FY 1999. Accordingly, the FY 1999 budget request includes an additional $57 million, beyond what otherwise would have been requested, to sustain the option of continuing START I levels of strategic nuclear forces.


Until START II enters into force, the United States will protect options to maintain a strategic nuclear arsenal consisting of the following:

500 Minuteman III and 50 Peacekeeper ICBMs with multiple warheads.

18 Ohio-class ballistic-missile submarines (SSBNs), each carrying 24 SLBMs.

At least 71 B-52 bombers, each equipped to carry up to 20 nuclear cruise missiles.

21 B-2 bombers, each equipped to carry up to 16 nuclear gravity bombs.

If START II is implemented with the Protocol to the Treaty, the U.S. arsenal will be modified by the end of the year 2007 as follows:

The Peacekeeper force will be eliminated and each Minuteman III missile will be armed with only one warhead.

Four SSBNs will be removed from strategic service.

The number of bombers will not change, but the cruise-missile capacity of the B-52 fleet will be reduced to stay within treaty limits.

The strategic nuclear delivery vehicles that will be eliminated under START II must be deactivated by December 31, 2003. With the modifications outlined above, the United States will be in compliance with START II limits, which permit a total of no more than 3,500 deployed strategic nuclear warheads, of which only 1,750 can be carried on SLBMs.

There has been a major reduction in the U.S. strategic nuclear arsenal in recent years. Table 11 compares the U.S. arsenals in FY 1990 and FY 1998 with the final limits under the START I and II treaties. All force levels are for the ends of the years in question.

Land-Based Intercontinental Ballistic Missiles

By the end of FY 1998, the United States will have 500 Minuteman III ICBMs and 50 Peacekeeper missiles. As noted previously, if START II enters into force, the United States will modify all Minuteman III missiles to carry only one warhead each and will retire all Peacekeepers. As part of this transition, the Department may transfer the Mark 21 warhead from the Peacekeeper to the Minuteman force. Mark 21 warheads contain additional safety-enhancing features that further reduce the risk of an accidental nuclear explosion and minimize the risk of plutonium dispersal in the event of a fire.

The United States is not developing or producing any ICBMs and has no current plans to develop any new ICBMs. This makes it difficult to sustain the industrial base needed to maintain and modify strategic ballistic missiles. To help preserve key industrial technologies needed to sustain ICBMs and SLBMs, the budget provides funding to preserve a core of expertise in the areas of reentry vehicle and guidance system technology.

Sea-Based Ballistic Missiles

The final Ohio-class SSBN was commissioned in 1997, bringing the U.S. SSBN fleet total to 18 Ohio-class submarines. The first eight Ohio-class submarines carry the Trident I (C-4) missile; the final ten are equipped with the Trident II (D-5) missile. The SSBN fleet’s survivability and effectiveness are enhanced through the D-5 missile’s improved range, payload, and accuracy. The FY 1999 budget provides for continued procurement of D-5 missiles to support the conversion of four SSBNs from the C-4 to the D-5 missile system. The retrofits will be accomplished during regularly scheduled ship depot maintenance periods, beginning in FY 2000. Under current plans, if START II enters into force, four submarines will be removed from strategic service, leaving 14 SSBNs armed with D-5s. These missiles, while capable of carrying eight warheads apiece, will be downloaded consistent with START II limits. No new SSBNs or SLBMs are under development.

Heavy Bombers

The U.S. bomber force currently consists of 94 B-1s, 94 B-52s, and 21 B-2s. Four of the B-2 bombers are being upgraded from a test to an operational configuration; the last of those aircraft will become operational in FY 2000. Both the B-2 and B-52 forces can be used for either nuclear or conventional missions. The B-1 force is now dedicated exclusively to conventional operations.


Table 11

Reductions in U.S. Strategic Nuclear Arsenal, FY 1990 Through 2007


FY 1990

FY 1998

(Dec 5, 2001)

(Dec 31, 2007)






Attributed Warheads on ICBMs



Not over 2,000







Attributed Warheads on SLBMs



Not over 3,456

Not over 1,750

Ballistic-Missile Submarines





Attributed Warheads on Ballistic Missiles



Not over 4,900

Not over 2,250

Heavy Bombers





a Excludes five decommissioned submarines (and their associated missiles and warheads) that were still START

b Excludes two Poseidon SSBNs converted to Special Operations Forces that are still START accountable.

c Excludes FB-111s.

d Excludes 94 B-1s that are devoted entirely to conventional missions.


Total Strategic Offensive Forces Funding Images and Strategic Offensive Forces Funding as a Percentage of Total DoD Funding Image

Reflecting the increased emphasis on nonnuclear operations, bomber modernization efforts are focused primarily on improving conventional warfighting capabilities. Accordingly, no new nuclear weapons for bombers are being produced or developed. Likewise, some nuclear air-launched cruise missiles (ALCMs) have been converted to conventional air-launched cruise missiles, and some gravity bombs and ALCMs have been retired or placed in dormant storage.

The recent Deep-Attack Weapons Mix Study (DAWMS) examined the contribution of bombers to conventional and nuclear warfighting scenarios. DAWMS considered several equal-cost options that would have expanded the B-2 fleet at the expense of planned force structure—land-based tactical aviation, aircraft carriers, or other bombers. The analysis showed that, for most of the cases examined, additional B-2s deployed quickly to a major theater conflict would improve the United States’ ability to halt an adversary’s advance during the early days. However, the analysis also demonstrated several disadvantages to trading off planned forces to procure additional B-2s. First, the B-2 would not, in most cases, offer either as much daily weapons delivery capacity or as full a range of capabilities as the forces it would replace. Moreover, existing forces would have to be retired immediately to pay for the additional B-2s—long before the B-2s would become available to provide compensating capability. Even then, savings from retiring forces would not offset the large up-front investment for B-2s until around 2017. Accommodation of additional B-2s under the START II limits also would require significant changes to the planned U.S. nuclear force structure. In view of these considerations and the findings of additional analyses, the QDR recommended against procuring additional B-2s. The FY 1999 budget and associated Future Years Defense Plan therefore include no funds for additional B-2 procurement.


Steps to ensure that the Minuteman III force can be maintained well into the next century are under way. For example, installation of new guidance subsystems will begin in FY 1999. Starting in FY 2001, Minuteman III solid rocket motors will be remanufactured to correct age-related degradation and to maintain system reliability.

U.S. ICBMs and those SLBMs at sea are maintained on continuous alert, but are not targeted at any specific country. The missiles could, however, be returned to their previous targeting status on short notice. The United States maintains two full crews for each SSBN, with about two-thirds of operational SSBNs routinely at sea. On average, about 10 percent of U.S. SSBNs are undergoing long-term overhauls at any given time, and thus are not available for immediate use. The bomber force is no longer maintained on constant alert, although it could be returned to alert status within a few days if necessary.


Funding for strategic nuclear forces—ICBMs, SLBMs, and nuclear bombers—has declined in recent years, as has the fraction of the total defense budget that is devoted to nuclear forces. Moreover, one of the weapon systems included in the nuclear force category—the B-1 bomber—has just completed its transition to a conventional role. Past and projected funding trends for strategic nuclear forces are highlighted in the charts on the preceding page.

Modernization programs for strategic forces largely have been completed or curtailed during the past few years. The only major acquisition efforts that remain are deliveries of the final four programmed B-2s, B-2 modifications (primarily for conventional missions), Trident II missile procurement, and Minuteman III life extensions. With most nuclear modernization efforts complete, programs to sustain force readiness now account for most strategic nuclear funding. The portion of the strategic budget devoted to operations and support has increased from about 40 percent of the total in 1991 to about 65 percent today and a projected 67 percent in 2003.


Strategic forces remain a critical element of the U.S. policy of deterrence. Although nuclear forces have been reduced in size and the percentage of the defense budget devoted to them has declined, strategic forces continue to provide a credible and valuable deterrent. The United States remains committed to appropriate and jointly agreed upon reductions in strategic nuclear forces, but will protect options to maintain its strategic capabilities at START I levels until the START II treaty has entered into force.

[Table of Contents][Go Back to Previous][Advance to Next][Top of Page]