I. Is There a Right of Preemptive Self-Defense?

A. The Right of Self-Defense

Under Article 2 (4), the UN Charter prohibits: “the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.”6 The UN Charter provides two exceptions for use of inter-State force:

1. when the Security Council has granted authorization under Chapter VII,7 or

2. in self-defense under Article 51.8 Article 51 provides the right to both individual and collective self-defense if an armed attack occurs.9

The prohibition of the threat or use of inter-state force, as well as the right of self-defense in reaction to an armed attack, are now accepted as part of customary international law.10

It is less clear whether the right of self-defense permits the use of nuclear weapons. In its 1996 Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons, the International Court of Justice stated that regardless of the means used in self-defense, the customary international law principles of necessity and proportionality, and other relevant rules of armed conflict, still apply.11 However, the Court was divided on how these principles and rules applied to nuclear weapons.12 The Court held that although the use of nuclear weapons “seems scarcely reconcilable” with the rules of armed conflict, it could not reach a definitive conclusion on whether their use would be at variance with the rules of armed conflict in any circumstance, particularly in self-defense “when [a State’s] survival is at stake.”13

B. The Right of Preemptive Self-Defense

1. Customary International Law

Some argue the right of preemptive self-defense has developed over centuries, perhaps dating back to as early as 1625, and is now widely accepted as customary international law.14 The Caroline incident of 1837 is often pointed to as the origin of the modern day right to anticipatory self-defense, when British soldiers seized an American ship in American waters for sending assistance to Canadian insurrectionists.15 US Secretary of State Daniel Webster’s response became known as the Caroline standard, and stated necessity, imminence, and proportionality were required to justify an act of anticipatory self-defense.16 In other words, a State must have no lesser alternatives to thwart an attack, no time to pursue nonmilitary alternatives, and if it does act, the force used must be the minimum required to repeal the attack.17

While many point to the Caroline standard as the origin for the right of anticipatory self-defense under customary international law, Yoram Dinstein argues this reliance is misplaced. Before Britain’s attack on the Caroline, the boat had been used regularly to transport men and supply materials to the anti-British uprising in Canada; moreover, the attack happened at a moment just “short of war.”18 He argues: “the question was not whether Britain had a right to go to war against the United States in the exercise of self-defense (after all, any State then had a right to go to war against another State for any reason),” but rather, “whether Britain could use forcible measures of self-defense within American territory without plunging the two countries into war.”19 Nonetheless, even if the Caroline standard is accepted as a statement of anticipatory self-defense, any preemptive nuclear strike would require necessity, imminence, and proportionality.20

Since the adoption of Article 51 of the UN Charter, the US has increasingly asserted a right to preemptive self-defense, particularly in response to the threat of nuclear weapons.21 In 2002, the US declared its policy on preemptive action in self-defense, known as the “Bush Doctrine,” which was “intended to ‘adapt the concept of imminent threat’ by allowing ‘anticipatory action’ to ‘forestall or prevent’ hostile acts.”22 This policy adapted the earlier concept of “imminent threat” to the danger posed by nuclear weapons and permitted preemptive action in self-defense even if there was still uncertainty about the opposing State’s impending attack.23 In December 2016, the Obama Administration asserted in its report guiding the US’s use of force: “the traditional conception of what constitutes an ‘imminent’ attack must be understood in light of the modern-day capabilities, techniques, and technological innovations of terrorist organizations.”24

2. UN Charter

Despite these statements, a preemptive nuclear strike based on an opposing State’s possession of nuclear weapons is not justified under international law. Any preemptive nuclear strike, even if it satisfies the Caroline criteria, would still need to comply with the UN Charter.25 And because the UN Charter requires self-defense as a reaction to another State’s use of force, there is no right to preemptive strikes even if the opposing State has indicated its will and capacity to launch a nuclear strike.26 For an act of self-defense to be lawful, assuming there has been no prior Security Council authorization, it must be in response to an attack already in motion.

3. Risk Factors

Moreover, providing a right of preemptive self-defense creates an alarming danger that that any false warning, accidental step, or misperceived military exercise could lead to war.27 For example, during the Cuban Missile Crisis, both the US and Soviet Union were prepared to launch preemptive attacks, creating a danger termed by strategist Thomas Shelling as “the reciprocal fear of surprise attack.”28 This fear was realized when a US U-2 spy plan accidentally flew through Soviet airspace; Khrushchev stated to President Kennedy that this plane could have easily been interpreted as a nuclear bomber and led the Soviet Union to attack.29

There is a similar, and even worse, danger with current situation between the US and North Korea. It may be difficult to distinguish between a preemptive-war plan and a first-strike plan: for example, would the movement of Pyongyang’s nuclear missiles out of storage be interpreted as a defensive precaution or the initiation of an attack?30 This risk increases with US President Donald Trump and North Korea’s leader Jong-un Kim, two leaders who are both “prone to lash out impulsively at perceived enemies, a tendency that can lead to reckless rhetoric and behavior.”31 Both South and North Korea have expressed their right of preemptive self-defense, which begs for greater clarity on whether this right exists under international law.32 The troubling reality is that any right of preemptive self-defense, even if it is a constrained right, heightens the risk of a global nuclear war.

4. Right of Interceptive Self-Defense

Although neither Article 51 of the UN Charter nor customary international law justify a preemptive nuclear strike, there is a right of interceptive self-defense that a State may invoke “in response to an armed attack at an incipient stage, as soon as it becomes evident to the victim State…that the attack is actually in the process of being mounted.”33 Dinstein argues that even if bombs have not fallen or shots have not been fired, a State has the right to intercept under Article 51 if it is certain an armed attack is under way (even in a preliminary manner).34

As a concrete example, Dinstein illustrates a hypothetical Pearl Harbor scenario: consider if the US had detected the Japanese Carrier Striking Force en route to its location to attack Pearl Harbor, contained reliable information regarding the nature of the mission, and attacked in response.35 Even if the US was the first to hit Japan, the US would not have been charged with inflicting an armed attack, but rather, determined as acting in interceptive self-defense.36

This restriction on the right of self-defense mitigates the risk of accidental war, while still providing a right to self-defense in the face of an impending attack. In accordance with Article 51 of the UN Charter, it provides the right of self-defense only in reaction to the use of force by an adverse State.37 It prevents attacks in response to threats that may be real, but perhaps not imminent, and minimizes the risk that a State will initiate an attack based on assumptions, speculation, or fear. Likewise, the UN High-Panel to Consider Collective Responses to Contemporary Threats argued:

In a world full of perceived potential threats, the risk to the global order and the norm of non-intervention on which it continues to be based is simply too great for the legality of unilateral prevention action, as distinct from collectively endorsed action, to be accepted. Allowing one to so act is to allow all.”38

5. Should There be a Right of Preemptive Self-Defense?

There is a strong counterargument that the unique and destructive power of nuclear weapons necessitates a reinterpretation of the traditional self-defense doctrine to prevent tremendous human suffering and damage.39 Under the Caroline standard, and its principles of imminence, necessity, and proportionality, many argue the current definition of imminence should be relaxed to account for the nature of a nuclear threat.40 In other words, given nuclear weapons’ potential to cause enormous destruction, a State should not be required to wait until it is attacked to act in protection of its own security. This is especially true where a State has made credible threats indicating its will and capacity to launch a nuclear strike.

However, the danger and uncertainty in allowing States to unilaterally decide when threats are credible enough to justify a preemptive strike outweigh these arguments. Precluding a right of preemptive self-defense, even when there are WMD involved, reflects not only the most accurate interpretation of international law, but also the most responsible. Consider the alternative: if State A has expressed its will and capacity to launch a nuclear strike and State B launches a preemptive nuclear strike based on its speculation of an attack somewhere in the future, State A will strike back, and the world will succumb to a global nuclear war. Because WMD have the capability to annihilate, it would be unwise to allow action based on a State’s unilateral determination that its security is at risk.

Determining whether a nuclear strike constitutes lawful interceptive self-defense or preemptive self-defense will require a fact-intensive inquiry to determine the exact moment of attack. It is critical that any act of self-defense is in reaction to an actual threat, not just the fear of one. The exact moment of initial attack will reveal the aggressor, whose use of force may then qualify as a crime of aggression within the ICC’s jurisdiction.

II. Preemptive Strikes and the Crime of Aggression

Dinstein argues that to pinpoint the exact moment of attack, it is necessary to look beyond the “first shot.”41 In other words, even if State A fires the first shot at State B, State B may have had troops invade the territory of State B days earlier. Here, State B would be the initial attacker and guilty of committing an act of aggression. Likewise, consider if State A aimed laser beams at State B’s target.42 Even if State A had not fired a missile yet, an armed attack would be deemed in progress, and State B may respond timely with an act of interceptive self-defense.43

While a preemptive strike may be in response to a mere threat or foreseeable attack, an interceptive strike is in response to “an armed attack which is already in progress, even if it is still incipient and its consequences have not yet been suffered.”44 In other words, a lawful act of self-defense cannot be in response to mere speculation or fear, but only when an armed attack is actually underway, even if not fully matured.45 In regards to the crime of aggression, this distinction is critical. If a strike is determined to have been preemptive, it may constitute a crime of aggression; but if a strike is determined to have been interceptive, it is a lawful act of self-defense.

If a use of force is found to be lawful self-defense, then it is excluded from the definition for the crime of aggression; if it is not lawful self-defense, then the Court will have to determine whether the act amounts to the crime of aggression. This analysis focuses on the third element of the crime referenced in the introduction: the act amounts to an act of aggression according to the definition in General Assembly Resolution 3314 and constitutes a manifest violation of the UN Charter.46

First, Article 8 bis provides that an “act of aggression” refers to “the use of armed force by a State against the sovereignty, territorial integrity or political independence of another State, or any other manner inconsistent with the Charter of the United Nations.”47 It lists seven acts that qualify as an act of aggression when committed by one State against another:

1. invasion or attack by armed forces against territory;

2. bombardment or use of weapons against territory;

3. blockade of ports or coasts by armed forces;

4. attack by armed forces on land, sea or air forces, or marine or air fleets;

5. use of armed forces in contravention of conditions provided in an agreement;

6. allowing territory to be used by another State to commit an act of aggression;

7. sending armed bands, groups, irregulars, or mercenaries to carry out acts of armed force.48

A preemptive nuclear strike falls within category (b).

However, for an act of aggression to qualify as a crime of aggression, the act, based on its character, gravity, and scale, must “constitute[] a manifest violation” of the UN Charter.49 Even if not present equally, the three conditions of character, gravity, and scale must be sufficient to justify a “manifest violation” of the Charter.50 Each condition evaluates an act of aggression from a different angle: “the intrinsic nature of the acts (‘character’), their seriousness (‘gravity’), and their magnitude (‘scale’).”51 These conditions indicate a high threshold for individual accountability, but it is still not clear how they will guide the Prosecutor’s decisions regarding what acts of aggression may qualify as a crime of aggression.52 However, the character, gravity, and scale of a preemptive nuclear strike would amount to more than a minor act of aggression and unequivocally constitute a threat to international peace and security.

III. Preemptive Nuclear Strikes, the US, and North Korea

A. The ICC’s Limits on Jurisdiction

It should be noted that because neither the US or North Korea are State Parties to the Rome Statute,53 there are important limitations on the exercise of the Court’s jurisdiction over any preemptive nuclear strike. The ICC could not exercise jurisdiction based on State Party or Prosecutor referral; it may only act upon a referral from the Security Council.54 And, common Paragraph 2 of Articles 15 bis and 15 ter exclude the ICC’s jurisdiction over past crimes of aggression; only acts that occur after two-thirds of States Parties decide to activate the Court’s jurisdiction may fall within the Court’s jurisdiction.55

Because it is outside the scope of this comment to examine the ICC’s jurisdictional limits in depth, I will proceed with my analysis under the assumption that if an act of aggression were to happen, the Court would have jurisdiction to act. Although this analysis focuses on the third element of the crime of aggression (whether there is an act of aggression in manifest violation of the UN Charter), it should be noted that in order for the Court to have jurisdiction over a preemptive nuclear strike by either the US or North Korea, the first two elements described in the introduction will also have to be satisfied.

B. Current State of Events

The current crisis between the US and North Korea has been described as a “Cuban Missile Crisis in Slow Motion,” yet more dangerous.56 Both the US and North Korea have indicated their capacity to launch a nuclear strike. Most recently, North Korea launched a new missile capable of traveling eight thousand miles and reaching anywhere in the US.57 US intelligence agencies believe North Korea has as many as sixty nuclear warheads.58 One assessment found that if the US enters nuclear war with North Korea, as many as one million people could die on the first day.59 The US has tried unsuccessfully to persuade North Korea to give up its nuclear weapons or missile program. Since 2006, there have been nine rounds of sanctions against North Korea, leaving much doubt that any further sanctions will be effective.60

In addition to their capacity, the US and North Korea have both indicated their will to initiate a nuclear strike. President Trump threatened if that North Korea made any more threats to the US, they will be met with “fire and fury like the world has never seen.”61 Trump has also stated that in case North Korea acts “unwisely,” the US military is “locked and loaded” to respond.62 Likewise, Kim Jong-un threatened to create “an enveloping fire” around Guam.63 And in an interview with an American journalist, Choe Kang-Il, a North Korean Senior Foreign Ministry official, stated:

If the US shows even a hint of a strike against North Korea, we will proceed with a preemptive attack on the US. To put it very simply, our county is just about on the eve of the outbreak of war.64

C. Interceptive Self-Defense or Crime of Aggression?

Many Americans are asking: if the US accepts complete denuclearization is impossible, and economic sanctions are ineffective, what options remain to defend itself against an imminent nuclear attack by North Korea?

Of particular importance to this question is an imminent attack. As explained above, it would be both unwise and incorrect to interpret international law in a way that would permit either the US or North Korea to initiate a nuclear strike unilaterally based on its belief that an attack is imminent. To do so would create far too much risk of an accidental war. Similar to the Cuban Missile Crisis where tensions are already enormously high, any small misstep could lead to global nuclear warfare.

Under international law, the US has the right of self-defense where it is interceptive, but not preemptive; only if North Korea initiates an attack can the US legally use force to intercept it. The application of this rule to any nuclear strike will not be clear cut, particularly because of the speed at which events may progress, and will depend on a fact-intensive inquiry into the exact moment of initial attack. Both sides will likely argue the other was the first aggressor. It will be the Prosecutor’s role to pinpoint the exact moment of initial attack and then evaluate whether the aggressor’s act constitutes a crime of aggression. In the case of a preemptive nuclear strike, it would likely qualify.

Without the right to act preemptively, if North Korea decides to launch a nuclear strike, there is risk the US will not be able to intercept it in enough time to prevent its destruction, and will instead respond with an additional nuclear strike that will cause even greater destruction. Millions of lives could be lost. Nevertheless, the risk in granting States’ a preemptive right of self-defense does not mitigate this danger, but may only make it worse. Deterrence appears to be the best option: the US should deter North Korea until it collapses under its own regime, just like the Soviet Union before it.65

IV. Conclusion

Despite the threat many States face in the age of WMD, neither Article 51 of the UN Charter nor customary international law provide a right of preemptive self-defense. Nonetheless, there is a right of interceptive self-defense that does not require shots to have been fired or bombs to have dropped, but only that an attack has been initiated. This limitation on self-defense influences the ambit of uses of force that may fall within the ICC’s jurisdiction under the crime of aggression. Dinstein argues it is plausible that “a day may come when States will agree to dispense completely with the use of force in self-defence, exclusively relying thenceforth on some central authority wielding an effective international police force.”66 If this day ever comes, then any nuclear strike, whether preemptive or interceptive, would constitute an act of aggression. But until that day, the determination of the legality of a nuclear strike will require a fact-intensive inquiry that pinpoints the moment of attack, and thereby, the aggressor. And hopefully, this will help prevent unleashing the fire and fury of global nuclear war.

Endnotes — (click the footnote reference number, or ↩ symbol, to return to location in text).

1. 1.

   Definition of the Crime of Aggression, The Global Campaign for Ratification and Implementation of the Kampala Amendments on the Crime of Aggression, [hereinafter Crime of Aggression], available online (last visited Dec. 2, 2017). ↩

2. 2.

   Id. ↩

3. 3.

   Rome Statute of the International Criminal Court, Adopted by the United Nations Diplomatic Conference of Plenipotentiaries on the Establishment of an International Criminal Court, Jul. 17, 1998, UN Doc. A/CONF.183/9, as amended [hereinafter Rome Statute], Art. 8 bis available online.. ↩

4. 4.

   Crime of Aggression, supra note 1. ↩

5. 5.

   See Yoram Dinstein, War, Aggression and Self-Defence 223 (6th ed. 2017).

   (It should be noted that both preemptive and anticipatory have been used to discuss the right of self-defense prior to an armed attack. Although their precise definitions may differ, for the purposes of this comment, I will use the terms interchangeably to refer to the use of force to prevent an adversary State’s imminent armed attack). ↩

6. 6.

   Charter of the United Nations, [hereinafter UN Charter], Article 2, available online. ↩

7. 7.

   Id. at Chapter 7, available online. ↩

8. 8.

   Id. at Article 51, available online. ↩

9. 9.

   Id. ↩

10. 10.

    See generally Case Concerning Military and Paramilitary Activites In and Against Nicaragua (Nicaragua v. U.S.), Merits, Judgment, 1986 I.C.J. Reports 14 (Jun. 27, 1986), available online. ↩

11. 11.

    See Dinstein, supra note 5, at 221. ↩

12. 12.

    Id. ↩

13. 13.

    Id. ↩

14. 14.

    Kelly J. Malone, Preemptive Strikes and the Korean Nuclear Crisis: Legal and Political Limitations on the Use of Force, 12 Pacific Rim L. Pol’y J. 807, 809 (May 2003), available online; see also David A. Sadoff, Striking a Sensible Balance on the Legality of Defensive First Strikes, 42 Vand. J. Transnat’l L. 441, 447–53 (Mar. 2009), available online. ↩

15. 15.

    Malone, supra note 14. ↩

16. 16.

    Sadoff, supra note 14, at 449. ↩

17. 17.

    Id. at 450–51. ↩

18. 18.

    Dinstein, supra note 5, at 225. ↩

19. 19.

    Id. ↩

20. 20.

    Malone, supra note 14, at 807. ↩

21. 21.

    Dinstein, supra note 5, at 222. ↩

22. 22.

    Id. ↩

23. 23.

    Malone, supra note 14, at 807. ↩

24. 24.

    The White House, Report on the Legal and Policy Frameworks Guiding the United States’ Use of Military Force and Related National Security Operations (Dec. 2016), available online. ↩

25. 25.

    Malone, supra note 14, at 807. ↩

26. 26.

    Id. ↩

27. 27.

    Scott D. Sagan, The Korean Missile Crisis: Why Deterrence Is Still the Best Option, 96 Foreign Aff. 72 (Nov. 2017), paywall. ↩

28. 28.

    Id. ↩

29. 29.

    Id. ↩

30. 30.

    Id. ↩

31. 31.

    Id. ↩

32. 32.

    Id. ↩

33. 33.

    Dinstein, supra note 5, at 222–8. ↩

34. 34.

    Id. at 228. ↩

35. 35.

    Id. at 231–2. ↩

36. 36.

    Id. ↩

37. 37.

    Id. at 228. ↩

38. 38.

    Jeffrey L. Dunoff, Steven R. Rattner & David Wippman, International Law: Norms, Actors, Process: A Problem-Oriented Approach 743–4 (4th ed. May 20, 2015). ↩

39. 39.

    Rachel A. Weise, How Nuclear Weapons Change the Doctrine of Self-Defense, 44 N.Y.U. J. Int’l L. & Pol. 1331, 1356 (2012), available online. ↩

40. 40.

    Id. ↩

41. 41.

    Dinstein, supra note 5, at 229. ↩

42. 42.

    Id. at 231. ↩

43. 43.

    Id. ↩

44. 44.

    Id. at 233. ↩

45. 45.

    Id. at 235. ↩

46. 46.

    Crime of Aggression, supra note 1. ↩

47. 47.

    Rome Statute, supra note 3. ↩

48. 48.

    Id. ↩

49. 49.

    Id. ↩

50. 50.

    Dinstein, supra note 5, at 143–44. ↩

51. 51.

    Id. at 144. ↩

52. 52.

    Id. at 144–45. ↩

53. 53.

    The States Parties to the Rome Statute, ICC, available online (last visited Feb. 8, 2018). ↩

54. 54.

    See Conditions for Action by the ICC, The Global Campaign for Ratification and Implementation of the Kampala Amendments on the Crime of Aggression, available online (last visited Feb. 8, 2018). ↩

55. 55.

    Rome Statute, supra note 3, at Art. 15 bis and Art. 15 ter. ↩

56. 56.

    David E. Sanger & William J. Broad, A ‘Cuban Missile Crisis in Slow Motion’ in North Korea, N.Y. Times, Apr. 16, 2017, available online. ↩

57. 57.

    Nicolas Kristof, Are We Headed Toward a New Korean War?, N.Y. Times, Nov. 29, 2017, available online.

    (Kristof notes that even if North Korea currently lacks the capacity “to attach a nuclear warhead to the missile so that it could survive the heat and friction of re-entering the atmosphere,” it is advancing towards that goal). ↩

58. 58.

    Sagan, supra note 27. ↩

59. 59.

    Id. ↩

60. 60.

    Kristof, supra note 57. ↩

61. 61.

    Maggie Astor & Christine Hauser, A Timely Guide to the North Korea Crisis, N.Y. Times, Aug. 10, 2017, available online. ↩

62. 62.

    Id. ↩

63. 63.

    Id. ↩

64. 64.

    Adam B. Ellick, John Woo & Jonah M. Kessel, From North Korea, With Dread, N.Y. Times, Nov. 28, 2017, available online. ↩

65. 65.

    Sagan, supra note 27. ↩

66. 66.

    Dinstein, supra note 5, at 223. ↩