Table of Contents
1.2. Tactical Nuclear Weapons during the Cold War
1.3. Tactical Nuclear Weapons after 9/11
2 Legality of the Use of Tactical Nuclear Weapons under International Humanitarian Law
2.1. The Prohibition of indiscriminatory attacks
2.2 The Prohibition of unnecessary suffering or injury
2.3 Protection of the Environment in Times of Armed Conflict
3 Conclusions and Outlook
In its 1996 advisory opinion regarding the legality of the use of nuclear weapons and the threat thereof, the International Court of Justice (I.C.J.) stated that, although the use and threat of use of nuclear weapons is incompatible with International Humanitarian Law (IHL), the United Nations’ (UN) highest judicial organ was unable to render an opinion on small nuclear weapons, since the Court had no information under which circumstances the use of such low-yield nuclear weapons was envisaged nor whether the use of small nuclear weapons would bear the risk of an escalation of the conflict in question to an all-out nuclear war. With the wars after 9/11, the development of nuclear weapons by North Korea and fears of the acquisition of a nuclear capability by Iran, this situation has changed in recent years. Tactical nuclear weapons became thinkable again, thus raising a number of issues in international law. This is particularly, but not exclusively, the case with regard to International Humanitarian Law. After the Bush Administration formulated a new Nuclear Posture Review which in part became public in March 2002, funding for research into the possibility to build nuclear ‘bunker buster’ bombs, i.e. bombs which could take out hardened and / or underground targets, was approved by the United States Congress on 12 November 2002. Low-yield nuclear weapons are generally said to be explosives with an output of less than 5 kilotons (kT).
Already before the political relations between Russia and the (now bigger) West deteriorated to the brink of a new Cold War in the course of the year 2014, Russia’s deployment of tactical nuclear weapons has been a continuing concern. In this article, the ideas behind the development of tactical nuclear weapons as well as the historical background are explained and their legality under IHL is questioned. While plans for the creation of new small nuclear weapons are said to have been shelved for now, the mere possibility of such weapons and the idea of a limited nuclear war make it necessary to research this issue.
1.2. Tactical Nuclear Weapons during the Cold War
One key Cold War scenario was the possible invasion of West Germany by Warsaw Pact forces. Given West Germany’s short East-West extension and the proximity of major targets such as Frankfurt and Hannover to the German-German border, nuclear battlefield weapons had been deployed in West Germany. They were meant to be used by West German and Allied forces in order to halt or at least slow down any Warsaw Pact invasion into West Germany before reinforcements would arrive. During the Cold War, a large number of Allied Forces were based in Germany but the North Atlantic Treaty Organization’s (NATO) war plans included the need to send more troops from other NATO states and in particular from North America to Germany in the event of an invasion, which was practiced annually in the so-called Return of Forces to Germany (REFORGER) exercises. The REFORGER exercises were at time so large that they triggered concerns in the USSR that they could be used as cover for an actual invasion to the Warsaw Pact states by NATO. The transport of Allied forces to Germany in the event of a Soviet invasion would take some time during which NATO forces already present in West Germany would have had to hold against the expected onslaught from the East. West Germany’s inability to trade territory for time lead to the idea to use small nuclear weapons on the battlefield in the Eastern parts of West Germany. One (but by no means the only) example of nuclear battlefield artillery was the a type of “nuclear bazooka” commonly referred to by NATO forces as “Davy Crockett”. The Davy Crockett was a portable nuclear battlefield weapon, which was to be transported on a jeep and operated by a team of two. It had one 0.01 or 0.02 kT warhead. The concept behind it was as simple as astonishing: immediately after the beginning of a massive ground invasion from the East, a small team would drive from Allied bases near the border towards the advancing Warsaw Pact invasion force; a few miles before actually making contact with the enemy force, a small nuclear warhead would be fired towards the invasion force and the Allied troops would retreat immediately in order to escape the nuclear blast they had just unleashed on the enemy. Even without the use of strategic nuclear weapons, parts of West Germany would have been reduced to a nuclear wasteland in order to slow down the Soviet advance long enough for other forces to be ready to repel the attack and for reinforcements to arrive across the Atlantic. In addition, the use of nuclear mines and nuclear warheads e.g. on “Lacrosse” and “Lance” missiles, had been considered by the West during the Cold War but nuclear battlefield weapons systems were part of the arsenals of both sides - and continue to play a role in the arsenals of both the United States and the Russian Federation. It appears save to assume that most nuclear powers have the technological ability to design and produce nuclear battlefield weapons, if so desired. While this requires a relatively small warhead, examples such as the Lance missile or the potential for putting a nuclear warhead on Scud missiles shows that the warhead can remain sizable. Building nuclear artillery systems does not require the know-how which went into the creation of weapons like the Davy Crockett which US forces were supposed to use against a Soviet invasion.
In 1994, after the end of the Cold War, the United States banned research on such small nuclear weapons. This made sense because the existence of small nuclear weapons created the possibility of a local, tactical, nuclear strike, which could trigger a nuclear response by other states which do not have this tactical nuclear option but ‘only’ strategic nuclear weapons such as nuclear bombs and missile based nuclear weapons. The idea of mutually assured destruction (MAD), which prevailed during the Cold War, does not apply to small nuclear weapons in the same way. This is especially the case if the technology is not widely available among hostile actors.
A side-effect of a proliferation is the risk of accessibility of small, portable, nuclear devices by terrorists. Already today, there is a permanent risk of radiological attacks due to the ease of access to nuclear material, e.g. from medical devices, be it through a “dirty bomb” or through simply placing nuclear material in a public place.
 International Court of Justice, Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion of 8 July 1996, I.C.J. Reports 1996, available online at http://www.icj-cij.org/docket/files/95/7495.pdf. (All links are up to date as of 23 August 2014.)
 Ibid., para. 105 (2) E.
 Cf. United nations. Main Bodies, about the International Court of Justice, http://www.un.org/en/mainbodies/.
 International Court of Justice (note 1), para. 94.
 On the development of nuclear weapons in North Korea, see Larry A. Niksch. North Korea's Nuclear Weapons Development and Diplomacy (2010).
 With regard to the risks of a nuclear Iran, see Eric S. Edelman, Andrew F. Krepinevich Jr., Evan Braden Montgomery. The Dangers of a Nuclear Iran. The Limits of Containment, in: Foreign Affairs, January/February 2011 issue, http://www.foreignaffairs.com/articles/67162/eric-s-edelman-andrew-f-krepinevich-jr-and-evan-braden-montgomer/the-dangers-of-a-nuclear-iran.
 Cf. Carlo Masala. Why a nuclear free world is neither realistic nor desirable, in: Europarl.europa.eu (2009), http://www.europarl.europa.eu/document/activities/cont/200912/20091215ATT66470/20091215ATT66470EN.pdf.
 On the Nuclear Posture Review of the Bush Administration, cf. Philipp Bleek. Nuclear Posture Review Released, Stresses Flexible Force Planning, in: Arms control today, January 2002, http://www.armscontrol.org/act/2002_01-02/nprjanfeb02.
 Christine Kucia. Congress Approves Nuclear 'Bunker Buster' Research, in: Arms Control Today, December 2002, http://www.armscontrol.org/Act/2002_12/bunkerbuster_dec02.asp.
 'Bunker busters' are also known as earth-penetrating weapons and are designed to hit underground targets, such as formerly safe bunkers.
 Kucia (note 9).
 The term “kiloton” refers to the equivalency with the explosive power of one thousand tons of Trinitrotoluene (TNT).
 John Borroughs. The Lawfulness of "Low-Yield", Earth-Penetrating Nuclear Weapons, available online at http://www.lcnp.org/wcourt/nwlawfulness.htm.
 See for example the 3 January 2014 report for the U.S. Congressional Research Service by Amy F. Woolf. Nonstrategic Nuclear Weapons, Congressional Research Service 7-5700 (2014), http://fas.org/sgp/crs/nuke/RL32572.pdf.
 No author named, Congressional Members and Nat'l Security Say Bush's Costly and Counterproductive Nuclear Weapons Plans Should Be Shelved, in: Arms Control Today, 7 May 2004, available online at http://www.armscontrol.org/pressroom/2004/May_2004.
 Historically on this event, see David Rennie. World War Three Seen Through Soviet Eyes, in: The Telegraph Online, 26 November 2005, http://www.telegraph.co.uk/news/worldnews/europe/poland/1504008/World-War-Three-seen-through-Soviet-eyes.html.
 Robert Gleason. The Nuclear Terrorist (2014), p. 179.
 For an in-depth description of the Davy Crockett, see J. R. Potts, M28/M29 Davy Crockett Tactical Nuclear Recoilless Gun (1961), in: Militaryfactory.com, 9 May 2012, available online at http://www.militaryfactory.com/smallarms/detail.asp?smallarms_id=570.
 No author named. Rückzug aus Europa, in: Der Spiegel, 24/1965, available online at http://www.spiegel.de/spiegel/print/d-46272947.html).
 No author named, Complete List of All U.S. Nuclear Weapons, entry "Mk-54", in: Nuclear Weapons Archive (2006), http://nuclearweaponarchive.org/Usa/Weapons/Allbombs.html.
 Cf. Jamie Wilson. Nuclear Mines to 'Stop the Soviets', in: The Guardian online, 17 July 2003, http://www.theguardian.com/uk/2003/jul/17/world.jamiewilson.
 The MGM-18 Lacrosse missile was designed for close-support of ground troops. The missile cold be equipped with a W40 nuclear warhead. (See no author named. Lacrosse Missile MGM-18, in: Brookings.edu, http://www.brookings.edu/about/projects/archive/nucweapons/lacrosse.
 For further information on the road-mobile MGM-52 Lance missile, see the entry MGM-52 Lance, in: MISSILE TREAT: A Project of the George C. Marshall and Claremont Institutes, http://missilethreat.com/missiles/mgm-52-lance.
 The Center for Arms Control and Non-Proliferation, U.S. Tactical Nuclear Weapons in Europe Fact sheet (2011), http://armscontrolcenter.org/issues/nuclearweapons/articles/US_Tactical_Nuclear_Weapons_Fact_sheet/.
 Federation of American Scientists, R-11 / SS-1B SCUD-A — R-300 9K72 Elbrus / SS-1C SCUD-B (2000), http://fas.org/nuke/guide/russia/theater/r-11.htm.
 The then West German Federal Minister of Defense Franz Josef Strauss had asked for Davy Crocketts to be handed over to West German Bundeswehr forces as well. Although NATO commander-in-chief General Laris Norstand initially supported that request, the American government refused to authorize German forces to handle the small nuclear weapon, cf. note 19.
 See Robert W. Nelson, Low-Yield Earth-Penetrating Weapons, in: 54 The Journal of the Federation of American Scientists 1 (2001), http://fas.org/faspir/2001/v54n1/weapons.htm.
 See e.g. Gabriela Martinez, Joshua Partlow, Stolen cobalt-60 found in Mexico; thieves may be doomed, Washington Post, 5 December 2013, http://www.washingtonpost.com/world/stolen-cobalt-60-found-in-mexico-curious-thieves-likely-doomed/2013/12/05/262ef990-5d66-11e3-8d24-31c016b976b2_story.html.
 "A “dirty bomb” is one type of a radiological dispersal device (RDD) that combines conventional explosives, such as dynamite, with radioactive material". (United States Nuclear Regulatory Commission, Fact Sheet on Dirty Bombs (2012), http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/fs-dirty-bombs.html.
 This method has been used by Chechen separatists in order to substantiate their claim of access to nuclear material: “In November 1995, Chechen rebel leader Shamil Basayev claimed that his forces had access to nuclear weapons and materials. To prove his claim, he guided a Moscow television crew to Izmailovsky Park in Moscow, where a container of radioactive cesium was discovered.” (David Albright, Kevin O’Neill and Corey Hinderstein. Nuclear Terrorism: The Unthinkable Nightmare, Institute for Science and International Security (2001), http://www.isis-online.org/publications/terrorism/overview.pdf, p. 3.)