Nicaragua vs the United States: Use of Force and Self-Defense (1 of 3)

Name of the Case: Case Concerning the Military and Paramilitary Activities In and Against Nicaragua (Nicaragua vs United States) 
The Court: International Court of Justice
Year of Decision: 1986. 

Note: This post will discuss the International Court of Justice’s (ICJ) discussions on the use of force and self-defence.If you would like to read about the jurisdictional issues relating to the multilateral treaty reservation of the United States and the ICJ’s reliance on customary law, please click here. For a diagram on some of the points discussed here, click here. It is recommended to use the diagram alongside this blog post.


The case involved military and paramilitary activities carried out by the US against Nicaragua from 1981 to 1984. Nicaragua asked the Court to find that these activities violated international law.

Facts of the Case:

In July 1979, the Government of President Somoza was replaced by a government installed by Frente Sandinista de Liberacion Nacional (FSLN). Supporters of the former Somoza Government and  former members of the National Guard opposed the new government. The US – initially supportive of the new government – changed its attitude when, according to the United States, it found that Nicaragua was providing logistical support and weapons to guerrillas in El Salvador. In April 1981 the United States stopped its aid to Nicaragua and in September 1981, according to Nicaragua, the United States “decided to plan and undertake activities directed against Nicaragua”.

The armed activities against the new Government was carried out mainly by (1)   Fuerza Democratica Nicaragüense (FDN), which operated along the border with Honduras, and (2) Alianza Revolucionaria Democratica (ARDE), which operated along the border with Costa Rica. Initial US support to these groups fighting against the Nicaraguan Government (called “contras”) was covert. Later, the United States officially acknowledged its support (for example: In 1983 budgetary legislation enacted by the United States Congress made specific provision for funds to be used by United States intelligence agencies for supporting “directly or indirectly military or paramilitary operations in Nicaragua”).

Nicaragua also alleged that the United States is effectively in control of the contras, the United States devised their strategy and directed their tactics, and that the contras were paid for and directly controlled by the United States. Nicaragua also alleged that some attacks against Nicaragua were carried out, directly, by the United States military – with the aim to overthrow the Government of Nicaragua. Attacks against Nicaragua included the mining of Nicaraguan ports, and other attacks on ports, oil installations, and a naval base. Nicaragua alleged that aircrafts belonging to the United States flew over Nicaraguan territory to gather intelligence, supply to the contras in the field, and to intimidate the population.

The United States did not appear before the ICJ at the merit stages, after refusing to accept the ICJ’s jurisdiction to decide the case. The United States at the jurisdictional phase of the hearing, however, stated that it relied on an inherent right of collective self-defence guaranteed in A. 51 of the UN Charter when it provided “upon request proportionate and appropriate assistance…” to Costa Rica, Honduras, and El Salvador in response to Nicaragua’s acts of aggression against those countries (paras 126, 128).

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F1: Map of Nicaragua, Costa Rica, Honduras and El Salvador. Source: Google Earth

Questions before the Court:
  1. Did the US violate its customary international law obligation not to intervene in the affairs of another State, when it trained, armed, equipped, and financed the contra forces or when it encouraged, supported, and aided the military and paramilitary activities against Nicaragua?
  2. Did the US violate its customary international law obligation not to use force against another State, when it directly attacked Nicaragua in 1983 and 1984 and when its activities in point (1) above resulted in the use of force?
  3.  Can the military and paramilitary activities that the US undertook in and against Nicaragua be justified as collective self-defence?
  4. Did the US breach its customary international law obligation not to violate the sovereignty of another State, when it directed or authorized its aircrafts to fly over the territory of Nicaragua and because of acts referred to in (2) above?
  5. Did the USs breach its customary international law obligations not to violate the sovereignty of another State, not to intervene in its affairs, not to use force against another State and not to interrupt peaceful maritime commerce, when it laid mines in the internal waters and in the territorial sea of Nicaragua?


The Court’s Decision:

The US violated customary international law in relation to (1), (2), (4) and (5) above. On (3), the Court found that the United States could not rely on collective self-defence to justify its use of force against Nicaragua.

Relevant Findings of the Court:

1. The Court held that the United States violated its customary international law obligation not to use force against another State when its activities with the contras resulted in the threat or use of force  (see paras 191-201). 

The Court held that:

(1) “most grave forms of the use of force” (i.e. those that constitute an armed attack); and

(2) “other less grave forms” of the use of force (i.e. organizing, instigating, assisting, or participating in acts of civil strife and terrorist acts in another State – when the acts referred to involve a threat or use of force, but not amounting to an armed attack). (Para 191), 

  • The United States violated the customary international law prohibition on the use of force when it laid mines in Nicaraguan ports. It also violated this prohibition when it attacked Nicaraguan ports, oil installations, and a naval base (see below). The United States could only justify its action on the basis of collective self-defence, if certain criteria were met (these criteria are discussed below).
  • The United States violated the customary international law prohibition on the use of force when it assisted the contras by “organizing or encouraging the organization of irregular forces and armed bands… for incursion into the territory of another state” and participated “in acts of civil strife…in another State”  and when these acts involved the threat or use of force.
  • The supply of funds to the contras did not violate the prohibition on the use of force. On the contrary, Nicaragua had previously argued before the Court that the United States determined the timing of offensives against Nicaragua when it provided funds to the contras. The Court held that “…it does not follow that each provision of funds by the United States was made to set in motion a particular offensive, and that that offensive was planned by the United States.” The Court held further that the arming and training of the contras and the supply of funds, in itself, only amounted to acts of intervention in the internal affairs of Nicaragua and did not violate the prohibition on the use of force (para 227) (again, this aspect will be discussed in detail below).

2. The Court held that the United States violated its customary international law obligation not to use force against another State when it directly attacked Nicaragua in 1983 and 1984 (see paras 187 – 201).

Note: A controversial but interesting aspect of the Court’s judgement was its definition of an armed attack. The Court held that an armed attack included:

(1) action by regular armed forces across an international border; and

(2) “the sending by or on behalf of a State of armed bands, groups, irregulars or mercenaries, which carry out acts of (sic) armed force against another State of such gravity as to amount to (inter alia) an actual armed attack conducted by regular forces, or its (the State’s) substantial involvement therein”.

Note also that that he second point somewhat resembles Article 3(g) of the UNGA Resolution 3314 (XXIX) on the Definition of Aggression.

The Court further held that:

  • Mere frontier incidents will not considered as armed attacks, unless, because of its scale and effects, it would have been classified as an armed attack had it been carried out by regular forces.
  • Assistance to rebels by providing weapons or logistical support did not constitute an armed attack. Instead, it can be regarded as a threat or use of force or an intervention in the internal or external affairs of other States (see paras 195, 230).
  • Under Article 51 of the UN Charter and under CIL – self-defence is only available against a use of force that amounts to an armed attack (para 211). 

Note:  In  in the ICJ’s Case Concerning Oil Platforms and the ICJ’s Advisory Opinion on the Legal Consequences of of the Construction of a Wall in the Occupied Palestinian Territory (hereinafter called the Palestine wall case) the ICJ confirmed the definition of  an “armed attack” as proposed in the Nicaragua case. Draft Articles on State Responsibility, prepared by the International Law Commission, provides significant guidance as to when acts of non-State actors may be attributed to States. These articles, together with recent State practice relating attacks on terrorists operating from other countries may have widened the scope of an armed attack, and consequently, the right of self defence, envisaged by the ICJ. (for example, see discussion surrounding the United States’ attacks in Afghanistan and Iraq) See also a paper by Max Plank Institute on this topic (2017).

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F 2. The most serious use of force and its consequences. Full diagram is here.
3. The Court held that the United States could not justify its military and paramilitary activities on the basis of collective self-defence.

Note that Article 51 of the UN Charter sets out the treaty based requirements on the exercise of the right of self-defense. It states:

“Nothing in the present Charter shall impair the inherent right of individual or collectiveself-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security. Measures taken by Members in the exercise of this right of self-defence shall be immediately reported to the Security Council.”

The Court held that:

(1) Whether the circumstances required for the exercise of self-defence existed; and

(2) Whether the steps taken by the State, which was acting in self-defence, corresponds to the requirements of international law.

(1)  A State must have been the victim of an armed attack;

(2)  That State must declare itself as a victim of an armed attack. The assessment on whether an armed attack had taken place or not, is done by the State who was subjected to the attack. A third State cannot exercise a right of collective self-defence based that third State’s own assessment;

(3)  In the case of collective self-defence, the victim State must request for assistance. The Court held that “there is no rule permitting the exercise of collective self-defence in the absence of a request by the State which regards itself as the victim of an armed attack”;

(4)  A State that is attacked, does not, under customary international law, have the same obligation as under Article 51 of the UN Charter to report to the Security Council that an armed attack happened – but the Court held that “the absence of a report may be one of the factors indicating whether the State in question was itself convinced that it was acting in self-defence” (see paras 200, 232 -236).

“…Whatever influence the Charter may have had on customary international law in these matters, it is clear that in customary international law it is not a condition of the lawfulness of the use of force in self-defence that a procedure so closely dependent on the content of a treaty commitment and of the institutions established by it, should have been followed. On the other hand, if self-defence is advanced as a justification for measures which would otherwise be in breach both of the principle of customary international law and of that contained in the Charter, it is to be expected that the conditions of the Charter should be respected. Thus for the purpose of enquiry into the customary law position, the absence of a report may be one of the factors indicating whether the State in question was itself convinced that it was acting in self-defence (See paras 200, 232 -236)”.

  • The Court, then, looked extensively into the conduct of Nicaragua, El Salvador, Costa Rica, and Honduras to determine if (1) an armed attack was undertaken by Nicaragua against the three countries, which in turn would (2) necessitate those countries to act in self-defence against Nicaragua (paras 230  – 236). The Court noted that (1) none of the countries who were allegedly subject to an armed attack by Nicaragua declared themselves as victims of an armed attack; (2) they did not request assistance from the United States to exercise its right of self-defence; (3) the United States did not claim that when it used force, it was acting under Article 51 of the UN Charter; and (4) the United States did not report that it was acting in self-defense to the Security Council. The Court concluded that, based on the above, the United States cannot justify its use of force as collective self-defence.
  • In any event, the Court held that the criteria relating to necessity and proportionality, that is  required to be met when using force in self-defence – were also not fulfilled (para 237).


 4. The Court held that the United States breached its CIL obligation not to intervene in the affairs of another State, when it trained, armed, equipped and financed the contra forces or encouraged, supported and aided the military and paramilitary activities against Nicaragua. 

The Court held that:

  • The principle of non-intervention requires that every State has a right to conduct its affairs without outside interference. In other words, the principle “…forbids States or groups of States to intervene directly or indirectly in internal or external affairs of other States.” This is a corollary of the principle of sovereign equality of States. The Court held that:

“A prohibited intervention must accordingly be one bearing on matters in which each State is permitted, by the principle of State sovereignty to decide freely. One of these is the choice of a political, economic, social and cultural system, and the formulation of foreign policy. Intervention is wrongful when it uses methods of coercion in regard to such choices, which must remain free ones. The element of coercion, which defines, and indeed forms the very essence of, prohibited intervention, is particularly obvious in the case of an intervention which uses force, either in the direct form of military action, or in the indirect form of support for subversive or terrorist armed activities within another State (para 205).”

  • Nicaragua stated that the activities of the United States were aimed to overthrow the government of Nicaragua, to substantially damage the economy and to weaken the political system with the aim to coerce the Government of Nicaragua to accept various political demands of the United States. The Court concluded that:

 “…first, that the United States intended, by its support of the contras, to coerce the Government of Nicaragua in respect of matters in which each State is permitted, by the principle of State sovereignty, to decide freely (see paragraph 205 above) ; and secondly that the intention of the contras themselves was to overthrow the present Government of Nicaragua… The Court considers that in international law, if one State, with a view to the coercion of another State, supports and assists armed bands in that State whose purpose is to overthrow the government of that State, that amounts to an intervention by the one State in the internal affairs of the other, whether or not the political objective of the State giving such support and assistance is equally far reaching.”

  • The financial support, training, supply of weapons, intelligence and logistic support given by the United States to the contras violated the principle of non-interference. “…(N)o such general right of intervention, in support of an opposition within another State, exists in contemporary international law”, even if such a request for assistance is made by an opposition group of that State (see para 246 for more).
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F 3. The prohibition on non intervention. For full diagram, click here.
  • However, in a controversial finding, the Court held that the United States did not devise the strategy, direct the tactics of the contras or exercise control on them in manner so as to make their acts committed in violation of international law imputable to the United States (see in this respect “Determining US responsibility for contra operations under international law” 81 AMJIL 86). The Court concluded that “a number of military and paramilitary operations of the contras were decided and planned, if not actually by United States advisers, then at least in close collaboration with them, and on the basis of the intelligence and logistic support which the United States was able to offer, particularly the supply aircraft provided to the contras by the United States” but not all contra operations reflected strategy and tactics wholly devised by the United States.

“…the various forms of assistance provided to the contras by the United States have been crucial to the pursuit of their activities, but is insufficient to demonstrate their complete dependence on United States aid. On the other hand, it indicates that in the initial years of United States assistance the contra force was so dependent. However, whether the United States Government at any stage devised the strategy and directed the tactics of the contras depends on the extent to which the United States made use of the potential for control inherent in that dependence. The Court already indicated that it has insufficient evidence to reach a finding on this point. It is a fortiori unable to determine that the contra force may be equated for legal purposes with the forces of the United States…The Court has taken the view (paragraph 110 above) that United States participation, even if preponderant or decisive, in the financing, organizing, training, supplying and equipping of the contras, the selection of its military or paramilitary targets, and the planning of the whole of its operation, is still insufficient in itself, on the basis of the evidence in the possession of the Court, for the purpose of attributing to the United States the acts committed by the contras in the course of their military or paramilitary operations in Nicaragua. All the forms of United States participation mentioned above, and even the general control by the respondent State over a force with a high degree of dependency on it, would not in themselves mean, without further evidence, that the United States directed or enforced the perpetration of the acts contrary to human rights and humanitarian law alleged by the applicant State. Such acts could well be committed by members of the contras without the control of the United States. For this conduct to give rise to legal responsibility of the United States, it would in principle have to be proved that that State had effective control of the military or paramilitary.”

  • Interesting, however, the Court also held that providing “…humanitarian aid to persons or forces in another country, whatever their political affiliations or objectives, cannot be regarded as unlawful intervention, or as in any other way contrary to international law” (para 242).
  •  In the event one State intervenes in the affairs of another State, the victim State has a right to intervene in a manner that is short of an armed attack (210).

“While an armed attack would give rise to an entitlement to collective self-defence, a use of force of a lesser degree of gravity cannot as the Court has already observed (paragraph 211 above) produce any entitlement to take collective countermeasures involving the use of force. The acts of which Nicaragua is accused, even assuming them to have been established and imputable to that State, could only have justified proportionate counter-measures on the part of the State which had been the victim of these acts, namely El Salvador, Honduras or Costa Rica. They could not justify counter-measures taken by a third State, the United States, and particularly could not justify intervention involving the use of force.”

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F 4. The less grave forms of use of force and its consequences. Full diagram is here.


5. The United States violated its customary international law obligation not to violate the sovereignty of another State, when it directed or authorized its aircrafts to fly over Nicaraguan territory and when it laid mines in the internal waters of Nicaragua and its territorial sea.

  • The  Court examined evidence and found that in early 1984 mines were laid in or close to ports of the territorial sea or internal waters of Nicaragua “by persons in the pay or acting ion the instructions” of the United States and acting under its supervision with its logistical support.  The United States did not issue any warning on the location or existence of mines and this resulted in injuries and increases in maritime insurance rates.
  • The Court found that the United States also carried out high-altitude reconnaissance flights over Nicaraguan territory and  certain low-altitude flights, complained of as causing sonic booms.  It held that a State’s sovereignty extends to its internal waters, its territorial sea, and the airspace above its territory. The United States violated customary international law when it laid mines in the territorial sea and internal waters of Nicaragua and when it carried out unauthorised overflights over Nicaraguan airspace by aircrafts that belong to or was under the control of the United States.. 
Material on the Nicaragua case

Nicaragua vs United States: Summary Diagram for Use of Force (Full diagram in PDF)

The judgment including separate opinions of individual judges and summaries of the judgment and orders

Other reading material, including  summaries of articles and other materials that maybe relevant to understand this case further,  can be found at this page.

© Ruwanthika Gunaratne  at, 2008 – 2017. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner, and without attribution to the author, is strictly prohibited. Excerpts and links may be used, without authorization, provided that full and clear credit is given to Ruwanthika Gunaratne  with appropriate and specific direction to the original content.

42 thoughts on “Nicaragua vs the United States: Use of Force and Self-Defense (1 of 3)

  1. Hi Bushra,
    I have not done an analysis on the web site, as of yet. My recommendation is that you look for articles published in 1997 in international law journals – which may give you what you are looking for.
    In addition, there is a review of the judgement in International and Comparative Law Quarterly 46, (1997), pp 681-688. 91 AJIL has a series of articles that maybe useful for you.
    Hope this helps,

  2. Dr. Gunaratne –

    This is an excellent summary of the most investigated/cited elements of Nicaragua vs. United States.

    I am in the process of investing how the Court deals with the matter of determining that a rebel movement is an organ or acting on behalf of a third party state. This is part of broader research on breakaway governments and their heavily dependent relationships with other states.

    I would appreciate any general comments you have on this matter. The way I see it, the Court utilizes an incredibly strict standard approaching total control on the part of the state and total dependence on the part of the rebel organization.

    Do you know of some journal articles that have focused on this particular aspect of Nicaragua vs. United States?

    What I’ve got so far is here:

    1. Hi Matthew, Thank you for your comments. Congratulations on your blog. On you question regarding material on the Nicaragua case in relation to the contras see 81AMJIL 86 ( That entire volume of the AMJIL is on the Nicaragua case. If you cannot download it, send me an e-mail and I could forward a copy to you. You may also wish to browse other international law journals around 1986-87.
      One argument given for this strict approach is appeasement – see the above article of Boyle. He disagrees with the Court’s findings and argues that the Court took this stance to appease the US since the Court went ahead with the case amidst US opposition.
      It is also possible that the court took such a strict approach because it was looking at the relationship from the view point of self defence. One of the main conclusions of the Court was that self defence against a State (in this case, the US) is available, if an armed attack occurred.
      The court went on to define an armed attack in respect of attacks carried out by a non-State actors (see above). It then held that assistance to rebels in the form of provision of weapons or logistical support did not constitute an armed attack. I.e. what is not an armed attack cannot give the victim State the right to use force in self defence (it can trigger other proportionate countermeasures). The Court was possibly looking to restrict opportunities for States to trigger the use of force in self defence by adopting a strict definition.
      Other cases that you can look at include DRC vs Uganda where the two countries accused each other of supporting rebels of the other State and the Bosina vs Serbia (Genocide case).
      On the legal status of multiple governments in the same State in relation to an intervention I find this article quite good:
      On the aspect of effective control over a person, although not directly relevant, I find this recent article by Novak interesting:
      In respect of State responsibility for acts of non-State actors, I find A. 4 -11 of the Articles on State Responsibility drafted by Crawford ( and the GA Declarations on Friendly Relations and Aggression quoted in the Nicaragua case helpful.

      1. Thanks! I believe I will be able to get the full journal through Tel Aviv University’s databases, though I will gladly take you up on the offer of receiving an e-mailed copy if it proves impossible.

        Thank you so much for the other links. Congo vs. Uganda is fascinating to me because of it’s applicability to the Israeli-Palestinian conflict. The Court’s line of reasoning without question would rule out the possibility of Gaza being occupied territory (If Uganda wasn’t an occupying power despite having a *friendly* local force on the ground, then a fortiori one must say the same about an unfriendly force on the ground.) I will be covering that case on my blog shortly.

        What is your opinion on the issue of the admissibility of law existing as both custom and treaty as applied to Nicaragua vs. USA? I’ve found the debate fascinating as it cuts to the core of the philosophy of law. It is clearly an ontological question. Personally, I did not find convincing Schwebel’s dissent (holding that customary law also existing in treaty was rendered inadmissible due to the U.S. reservation). There was clearly no evidence that the U.S. considered it’s reservation as applicable in such a matter. Obviously, we should be able to see some internal documents from the U.S. indicating such intent.

        1. Just to clarify – I mean there was no evidence ***at the time the US made the reservation***, clearly the U.S. argued during the trial that its reservation applied to custom.

          1. Hi Mattew, Yes, I agree. The argument by the US was that treaty law subsumes and supervenes identical customary law. There were a lot of articles criticising the Court’s decision to go into the merit stage at the time, but I believe it was correct. Had the US intended to oust customary law, it could have said so at the time of its reservation. You may find this interesting –

  3. can anyone help me regarding below question?
    are statements recorded on the floor of general assembly sources of international law?

    1. Statements may, at most, be indicative of opinio juris in establishing customary international law. Isolated from other and more substantial evidence of opinio juris, such statements amount to little.

      Do you have a specific example?

  4. i found it more precise and understndable as cases of international issues are diffucult to get the point this article however did it
    thank you

  5. Guys i need help i have an essay entitled: with the use of examples analyse the ICJs impartiality/ partiality in undertaking its mandate.

  6. ‘According to the framework set forth by the International Court of Justice in Nicaragua v. United States (1986), airstrikes can constitute an “armed attack” triggering the target state’s right to self-defense; but the arming and training of rebels does not on its own amount to an armed attack. [As an aside: the long-standing United States’ position on these matters, in contrast, is that any use of force (below the threshold of an armed attack) can also trigger the right of self-defense.]’. See ‘Having Crossed the Rubicon: Arming and Training Syrian Rebels’ at

  7. This is a great summary of the case. I have an assignmet on that case nd this summary helped me alot in my research..

  8. Was a little bit confused when I read the case extracts in my textbook. But this was clear and very easy to understand. Thanks so much!

  9. thank you for your advance!!!, i used this summarized case for my work, it is attractive and interesting. keep it up bro!!!!!

  10. Hello! Great article. Could you resume US arguments and it’s legal basis? I have a debate on my school and representing US. Because of that I’m trying to achieve a general knowledge on the subject before going into a deeper investigation.

  11. Hi. Can anyone please clarify what the para. in this article refer to? Are they the parapgraphs from the main judgment -if so can you please send the exact link of the source.

    Thank you,

  12. Thanks for giving clear elaboration on different cases and judgements of cases on those cases ..this exposes us to the wider understanding of the concept of international law

  13. Your article was very beautiful, very good to read, I got to learn a lot from your article and it is a good thing, we should always keep getting something to learn. I am getting to learn a lot from you too. Thanks for keeping us writing articles of manner.

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