|Fig. 1: President Kennedy signs the LTBT on October 7, 1963. (Source: Wikimedia Commons)|
Since 1963, the U.S. has entered into or engaged with a variety of international treaties regarding the use of nuclear technology, specifically as a weapon. While the exact terms, conditions, and signatories and the parties behind them have changed over the decades, every treaty holds one common goal: limiting the use and advancement of nuclear weapons and the destruction they can cause. Furthermore, there are two broad types of treaties the U.S. has entered into: test ban treaties, meant to limit the testing of nuclear weapons and their deleterious effects, and bilateral armament treaties with the U.S.S.R., meant to prevent the threat of Mutually Assured Destruction and nuclear war.
The U.S. along with many other countries has been involved in a variety of treaties meant to ban the testing of nuclear weapons. The first of these, which then-President John F. Kennedy stated to be "the first concrete result of 18 years of effort by the United States to impose limits on the nuclear arms race," is the 1963 Test Ban Treaty, also known as the Limited Test Ban Treaty (LTBT), the signing of which is seen in Fig. 1.  This treaty, while originally signed by three of the first nuclear states: The U.S., the U.K., and the U.S.S.R., has since seen dozens of other states sign on since its inception. Furthermore, this first treaty, though it states that its "principal aim [is] the 'complete disarmament' which would put an end to the armaments race and eliminate the incentive to the production and testing of all kinds of ... nuclear weapons," was in effect more concerned with reducing nuclear fallout, "desiring to put an end to the contamination of mans environment by radioactive substances."  Specifically, the treaty prohibits the testing of nuclear weapons in the atmosphere, outer space, or under water in order to limit radioactive fallout.
Furthermore, over the next few decades, the U.S. and the U.S.S.R. themselves engaged in several bilateral treaties meant to limit nuclear testing. These include the 1974 Threshold Test Ban Treaty (TTBT) and the 1976 Treaty on Underground Nuclear Explosions for Peaceful Purposes, also known as the Peaceful Nuclear Explosion Treaty (PNET). The TTBT set a maximum limit of 150 kilotons of TNT on the yield of underground nuclear explosions, which were still allowed by the LTBT. This treaty did have some roots in attempting to curtail the nuclear arms race: the 150 kiloton yield limit was set with full knowledge that the two countries were already developing and testing weapons of this magnitude, and aimed to stop the development of even more powerful weapons.  The PNET, intended to accompany and reassert parts of the TTBT, also included a mechanism of verification, permitting for the first time U.S. observers inside the U.S.S.R. to verify the arms control agreement.  However, the spirit of test banning seemed to have dried up by the 1990s. Though U.S. President Clinton was the first to sign the Comprehensive Test Ban Treaty (CTBT) in 1996, which has since been ratified by 157 countries, the U.S. Congress has not ratified the treaty which in part prohibits countries from causing nuclear explosions of any kind. 
|Fig. 2: The Nike Zeus Anti-Ballistic Missile Launch on September 4, 1960. (Source: Wikimedia Commons)|
Between the LTBT in 1963 and the 1974 TTBT, the U.S. and dozens of other countries signed perhaps the most famous nuclear weapon treaty: the Treaty on the Non-Proliferation of Nuclear Weapons, otherwise known as the Non-Proliferation Treaty (NPT). This treaty, unlike the aforementioned treaties, was not a simple test ban. Instead, the NPT, opened for signatures in 1968 and effective 1970, rests on three "pillars": nonproliferation, peaceful uses, and disarmament.  Under the first two pillars, the NPT allows countries to use and spread peaceful nuclear technology while disallowing countries to aid in the transfer or manufacture of nuclear weapons. In addition, going along with the stated intent of the LTBT, under the third pillar the NPT promotes disarmament. However, this third pillar does not, like the PNET does, provide for a verification mechanism, instead relying on the "good-faith negotiations" of the parties included in the treaty.  Nevertheless, the NPT is considered a milestone of nuclear treaties both for its content and its breadth, and with over 190 parties, is the most extensive nuclear treaty in force that the U.S. has joined. 
While many of the multilateral test ban treaties were being negotiated and signed, the U.S. and the U.S.S.R. also engaged in bilateral treaties regarding the armaments of the two countries. While the failure to pass the CTBT might indicate a trend away from abandoning nuclear weapons or momentum towards a heavily weaponized future, the overall restrictions and strength of the armament treaties between the two superpowers strengthen over time, indicating a trend towards decreasing palpable tensions and armament, especially after the escalating arms race of the 1970s and 1980s. However, that is not to say that the armament treaties were all enacted without a hitch; several prominent failures to pass these treaties and withdrawals from them color the history of cold war relations.
The bilateral armament treaties can be roughly categorized as stemming from two main negotiation series: the Strategic Arms Limitation Talks (SALTs) starting in the last few weeks of the 1960s, and the succeeding Strategic Armament Reduction Treaty (STARTs), which began negotiations in the 1980s.
The first round of SALT negotiations, known as SALT I, commenced in 1969, culminating two and a half years later in 1972 with two treaties, sometimes collectively referred to as the SALT Agreement or also as SALT, the Interim Agreement Between the United States and the Union of Soviet Socialist Republics on Certain Measures With Respect to the Limitations of Offensive Arms (Interim Agreement) and the Treaty on the Limitation of Anti- Ballistic Missile Systems (ABM Treaty) (Fig. 2). Together, these treaties saw progress in limiting both the offensive and defensive capabilities of both parties. The Interim Agreement, which froze at existing levels or limited the production of long-range ballistic missiles was "essentially [a] holding action" on arms production given its limited enforcement for five years.  While the Interim Agreement dealt with offensive capabilities, the ABM Treaty dealt with defensive ones. The ABM Treaty sought to limit the capabilities of anti-ballistic missiles: defensive missiles that could themselves shoot down longer-range ballistic missiles such as those carrying nuclear warheads. The ABM treaty specifically limited each side to a single ABM defensive system with no more than 100 interceptor missiles and 100 launchers. This treaty was meant to complement the interim agreement and together halt the arms race, since limiting each side's defensive capabilities would limit the need for offensive power as well. The ABM Treaty itself states this goal, noting that "effective measures to limit anti-ballistic missile systems would be a substantial factor in curbing the race in strategic offensive arms and would lead to a decrease in the risk of outbreak of war involving weapons."  In addition, the treaties included verification techniques to ensure the two countries' compliance.
|Fig. 3: President Carter and Secretary General Brezhnev sign SALT II Treaty on June 18, 1979. (Source: Wikimedia Commons)|
The second round of SALT began following SALT I in 1972 and concluded in 1979. The SALT II Treaty, more formally the Treaty between the United States of America and the Union of Soviet Socialist Republics on the Limitation of Strategic Offensive Arms, Together with Agreed Statements and Common Understanding Regarding the Treaty (SALT II), signed in 1979 by President Carter and General Secretary Brezhnev, aimed to target areas SALT I did not (Fig. 3). SALT II, for instance, was the first treaty to see a real reduction in arms, reducing the delivery vehicles of nuclear weapons to 2,250 for each country. SALT II also placed restrictions on Multiple Independently Targetable Reentry Vehicles (MIRVs), a missile technology that could overwhelm ABM defenses and force an arms race, and provided verification measures for all these things.  However, like the CTBC to come, this agreement was never ratified. Though President Carter requested that the Senate not ratify the treaty due ostensibly to the U.S.S.R.'s invasion of Afghanistan, a request which was obeyed, with similar ratification issues within the U.S.S.R., both states have nonetheless observed (for the most part) the treaty since its signing.  In this manner the spirit of disarmament continued and precedence in at least some form was set for future arms reduction.
Through the treaties stemming from the SALT negotiations, the two superpowers saw at first a limitation then an actual reduction in terms of arms, though negotiation problems did exist. The progress made in these talks would be continued in the 1980s and 1990s with START, though START would also see some of the same problems rehashed and would run into reminiscent ratification and negotiation issues. However, one important treaty came about in the 1980s before the fall of the Soviet Union. In 1987, the U.S. and the U.S.S.R signed the Intermediate- Range Nuclear Forces Treaty (INF Treaty), which banned an entire category of weapons (in this case, the eponymous intermediate-range nuclear weapons). The INF Treaty is especially significant since it was the first treaty to ban a category of weapons already deployed, the first treaty to call for an asymmetrical reduction in arms (the U.S.S.R. destroyed more missiles and warheads than the U.S.), and the first treaty to include invasive verification monitoring mechanisms.  In this way the INF helped lay groundwork for treaties laid out in the 1990s and after the turn of the century.
In 1991 the two superpowers signed the bilateral START I (formally, The Treaty Between the United States of America and the Union of Soviet Socialist Republics on the Reduction and Limitation of Strategic Offensive Arms), which saw an aggressive reduction of both ballistic missiles and warheads. In addition, in an asymmetrical move reminiscent of the INF Treaty, in order to reach a level of parity START I mandated that the U.S. destroy 365 of its B-52 bombers and provided a mechanism for the U.S.S.R. to verify this.  Like SALT II, START I not only saw a real reduction of weapons but provided a mechanism for verification of this disarmament.
|Fig. 4: Presidents Bush and Putin sign SORT on May 24, 2002. (Source: Wikimedia Commons)|
Though START I entered force in 1994 and was not set to expire until 2009, negotiations on the next treaty, START II, began between the U.S. and the Russian Federation (the primary successor state to the U.S.S.R. for purposes of treaties following the nation's collapse) began in 1992. START II, officially the Treaty Between the United States of America and the Russian Federation on the Further Reduction and Limitation of Strategic Offensive Arms, had its roots in START I, and as evidenced by the "Further" in its title, and was meant to complement START I. Also like START I, START II called for not just the limits of arms but a real reduction in their number. In addition, like the INF Treaty, which banned an entire category of weapons, START II called for the banning of all MIRV missiles. In this way START II can be seen as a continuation of SALT II, which limited the use of MIRVs. However, like SALT II, problems surrounding START II's entering into effect plagued the treaty. Though the leaders of the U.S. and Russian Federation signed START II, the two nations' legislatures ratified slightly different version of START II, leading to the treaty never fully entering into effect.  In addition, while the U.S. had officially observed START II since 1993, the Russian Federation did not officially ratify the treaty until 2000 and even then pulled out of START II in 2002, citing the U.S.'s withdrawal from the ABM Treaty as its impetus (the U.S. withdrew from the ABM just before its expiration earlier that year). 
These question marks surrounding START II impacted the negotiations on START III, which started in 1997. START III, which proposed further nuclear arms reductions, was dependent on START II taking effect.  Given the status of START II at the time, a treaty was never drafted and START III never left negotiations.
Instead, the two nations would sign the Strategic Offensive Reductions Treaty (SORT) in 2002, which came into force in 2003 (Fig. 4). SORT, officially The Treaty Between the United States of America and the Russian Federation On Strategic Offensive Reductions, also called the Moscow Treaty, saw the reduction of nuclear arms through limiting the number of operationally deployed warheads to the range of 1,700-2,200 for each party.  This is in contrast with START I, which limited the delivery mechanisms rather than the warheads. In addition, though SORT deals with limiting "operationally deployed" strategic nuclear forces, a subset of warheads under the preceding START rules, SORT still saw similar limits on warheads that were proposed under the failed START III. 
|Fig. 5: Presidents Obama and Medvedev sign New Start treaty on Apr 8, 2010. (Source: Wikimedia Commons)|
The START series saw its latest entry, and the most recent nuclear arms treaty signed between the U.S. and the Russian Federation, signed in 2010 with New START (officially, The Treaty Between the United States of America and the Russian Federation of Measures for the Further Reduction and Limitation of Strategic Offensive Arms) (Fig. 5). New START, which entered force in 2011 for 10 years, officially replaced SORT (set to expire in 2012) and succeeded START I (to which the "Further" in its title, like that in START II, references), which expired in 2009 (and also succeeding START II, which never officially or fully entered into force). Like its predecessors, New START saw an actual reduction: it cut in half the number of strategic nuclear missile launchers (a total of 800 ICBMs, SLBMs, and bombers) and by 30% the number of warheads (to 1,550).  These numbers are two-thirds less than the levels of START I and are 10% less than those of SORT. In addition, New START introduced a new verification mechanism, and though it does not outright limit the deployment of missile defense systems it allows the Russian Federation to withdraw from the treaty if the U.S. deploys considerable missile defenses; in addition, like SORT, New START does not limit the number of nuclear warheads stockpiled, of which the U.S. and the Russian Federation control 90% of in the world.  Nevertheless, New Start is the most recent and aggressive entry into the corpus of arms limitations treaties between the two world powers.
In a period spanning half a century, from the 1963 Limited Test Ban Treaty to 2010's New START, treaties concerning nuclear weapons have helped put a limit on the cold war arms race between the U.S. and its eastern opponent. From multilateral test bans to bilateral armament agreements, the two countries have in general seen a trend towards decreasing the scope and number of nuclear weapons, though this process was by no means linear or without interruption. Still, negotiations between these two parties are ever evolving, and even old treaties resurface in the 21st century: beyond the aforementioned withdrawals from the ABM Treaty by the U.S. and START II by the Russian Federation in 2002, the U.S. notified Russia in 2014 that it was in violation of the INF Treaty.  Though the world may never be free of nuclear weapons, and though countries like the U.S. seem uncomfortable giving up nuclear testing outright yet, the trend of reducing nuclear arms and limiting technologies may yet continue.
© Zachary Long. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 E. Schwelb, "The Nuclear Test Ban Treaty and International Law," Am. J. Int. Law 58, 642 (1964).
 "Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space and under Water," (TIAS 5433), United States Treaties and Other Agreements, 14 UST 1313 (1963).
 J. Goldblat, Arms Control: The New Guide to Negotiations and Agreements (International Peace Research Institute, 2002), pp. 51-52.
 "Announcement of Treaty on Underground Nuclear Explosions for Peaceful Purposes (PNE Treaty)," U.S. Arms Control and Disarmament Agency, 28 May 76.
 L. Krauss, "It's Time for the U.S. To Finally Sign the Nuclear-Test-Ban Treaty," Slate, 25 Apr 12.
 "Treaty on the Non-Proliferation of Nuclear Weapons," (TIAS 6839), United States Treaties and Other International Agreements, 21 UST 483 (1970).
 "Treaties in Force", United States Department of State, 1 Jan 13, p. 446.
 "Interim Agreement Between The United States of America and The Union of Soviet Socialist Republics on Certain Measures With Respect to the Limitation of Strategic Offensive Arms," (TIAS 7504) United States Treaties and Other International Agreements, 23 UST 3462 (1972).
 "Treaty Between the United States of America and the Union of Soviet Socialist Republics on the Limitation of Anti-Ballistic Missile Systems," (TIAS 7503) United States Treaties and Other International Agreements, 23 UST 3435 (1972).
 J. M. Lodal, "SALT II and American Security," Foreign Affairs 57, No. 2, 245 (1978).
 L. Sartori, "Will SALT II Survive?" Int. Security 10, No. 3, 147 (Winter, 1985-1986).
 A. F. Woolf, "Russian Compliance with the Intermediate Range Nuclear Forces (INF) Treaty: Background and Issues for Congress," Congressional Research Service, R43832, 13 Oct 15.
 A. H. Rotstein, "U.S. Air Force Turns B-52 Bombers Into Scrap Metal," Los Angeles Times, 11 Sep 94.
 S. LaFraniere, "Moscow Pulls out of START II," The Moscow Times, 17 Jun 02.
 "The START III Framework at a Glance," Arms Control Association, January 2003.
 "The Moscow Treaty," International Legal Materials 41, 799 (2002).
 D. Welna, "START Stalled: GOP Delaying Vote On Arms Treaty," NPR, 17 Nov 10.
 P. Baker, "Twists and Turns on Way to Arms Pact With Russia," International New York Times, 26 Mar 10.
 A. Luhn and J. Borger, "Moscow May Walk Out of Nuclear Treaty After US Accusations of Breach," The Guardian, 29 Jul 14.