Dr. Atul Alexander*

Keywords:   ARSIWA – Chicago Convention – Countermeasure – Force Majeure – UN Charter

Recently the United States (U.S) shot down the Chinese High Altitude Balloon (HAB) in the sovereign airspace of the U.S. According to the U.S. Secretary of Defense Llyod Austin, the HAB was deployed to carry out surveillance activities in the continental U.S. The incident forced the Secretary of State Anthony Blinken to comment how China had breached the fundamental principles of international law and also postponed his diplomatic visit to China. 

In the aftermath of the incident, several scholars argued how China violated international law; this post explores how both U.S and China breached international law obligations. The Chinese claim that the balloon was used for civilian purposes for undertaking scientific research. Moreover, it contended that it could not prevent the balloon from drifting because the westerly wind movement influenced the balloon’s scheduled route. As China puts it, the infringement was a case of force majeure. It is without a doubt that the incursion of the balloon tested the boundaries of international law. 

Force Majeure Exception

The initial Chinese statement claims that as the balloon was in distress, it was entitled to enter the U.S. sovereign airspace. Since the balloon was used for civilian purpose (as per Chinese reports) it does not enjoy sovereign immunity.  In terms of distress, Art. 23(1) of Articles on Responsibility of States for Internationally Wrongful Acts states (ARSIWA) states in substance that- the wrongfulness of the act committed by a State is precluded, if the act is due to force majeure, that is, the occurrence was because of irresistible force or unforeseen event, which is beyond the control of the State. This is a scenario wherein the State is compelled to act in a way inconsistent with the international law obligation incumbent upon it. To invoke force majeure, there are three fundamental requirements; (a) the act must be brought because of the irresistible force of nature, (b) it has to be beyond the control of the State, and (c) it becomes materially impossible in the circumstances to perform the obligation. Assuming that the balloon drifted because of the westerly winds, it certainly fits into the first requirement. It can be said that the movement of the balloon is beyond the control of the Chinese authorities, and hence, it became materially impossible for China to fulfil the international law obligation. 

The U.S. could assert that China was in breach of the principles under the general international lawand the Convention on International Civil Aviation 1944 (Chicago Convention). State practice reveals that force majeure applies in situations of actual impossibility and not difficulty of performance plea. The International Law Commission (ILC) commentary provided examples of distress to include cases of aircraft entering the airspace of other states because of loss of control or weather. The exception to the said rule is when the State invoking the exception has actively contributed to the material impossibility and thereby accepted the risk of the occurrence of force majeure. As Michel Bourbonniere and Louis Haeck point out, “The overflight of sovereign territory by a state aircraft can be justified by reasons of distress or force majeure as an exception to the principle [that state aircraft cannot flyover the territory of another State…without authorisation.” However, according to Article 8of the Chicago Convention, pilotless aircraft are required to get special authorisation from the contracting State over which the aircraft is flown, this is also espoused by the U.S. statute wherein the federal government maintains exclusive sovereignty over U.S. airspace, and foreign aircraft require permission to navigate.

One of the annexing agreements under the Chicago Convention is the International Air Services Transit Agreement, the agreement provides for multilateral exchanges with regard to the first two freedoms of the air with regard to schedule air services. The Convention and the annexing agreement meant that each State recognized the other’s right to fly through national air space. Although China has denounced the agreement on 11 December 1946, through its note of 3 June  1997, the Chinese Ambassador, stated that the agreement ‘applies to Hong Kong at present, will continue to apply to the Hong Kong Special Administrative Region with effect from July 1997.’ Also, by the note dated 8 December 1999, it applied to the Macau region. Moreover, the freedoms mentioned in the Transit Agreement are with respect to scheduled air services. Accordingly, the applicability of rights under the Transit Agreement in this case becomes questionable.

The Legality of United States Actions

As per Article 1 of the Chicago Convention, every State has complete and exclusive sovereignty over airspace above its territory. Annex VII of the said convention defines an aircraft as “any machine that can derive support in the atmosphere from the reactions of the air other than the reactions of the air against the earth’s surface.” The definition under the Chicago Convention’s Annex VII includes object lighter or heavier than air and powered or unpowered balloons. Further, paragraph 2.2 of Appendix 5(Annex II) of the Chicago Convention states how an unmanned free balloon used exclusively for meteorological purposes shall not be operated across the territory of another State without appropriate authorisation. Further, paragraph 2.3 provides that authorisation is to be taken prior to launching the balloon if there is a reasonable expectation…that the balloon may drift over the airspace of another State. It is evident from the existing fact that China didn’t get prior authorisation from the U.S.

After the downing of the KAL 007 on 1 September 1983, members of the ICAO assembly adopted Art 3 bis to the Chicago Convention, wherein, if there are reasonable grounds to conclude that an aircraft is being used for any purpose inconsistent with the purpose of the Convention, instructions are to be given to the aircraft to end the violation. In doing so, a State may resort to appropriate means according to relevant rules of international law. In essence, Article 3 bis precludes States from using weapons against intruding aircraft. It is widely agreed that Art 3 bis is a codification of customary international law. Also, the point to be noted is that Art. 3 bis does not intend to modify the rights and obligations of the State under the UN Charter. Therefore, the U.S could attempt to make a valid justification for the use of force under Art. 51 of the UN Charter.

Article 51 permits States to use force for self-defence in case of an armed attack against it.  In the Oil Platforms Case (2003) between Iran and U.S, the International Court of Justice (ICJ) articulated the jurisprudence on ‘armed attack’; accordingly,  it expressed, in exercise of the right of individual self-defence, States have to prove that attack against it is of such a nature to be qualified as an ‘armed attack’ within the meaning of Art. 51. Literal reading of Art. 51 would indicate that an armed attack has to be essentially kinetic in nature. Hence, self-defence taken devoid of a previous act of an armed attack (in a kinetic sense) is untenable. 

Further, to trigger Article. 51, the requirement of proportionality, necessity and immediacy are to be fulfilled. Even if the Chinese Balloon entered U.S. airspace, it did not use force, a prerequisite to trigger Article 51 and to press into application the proportionality and necessity threshold. The ICJ has shed light on the nature of self-defence in the NicaraguaCase (1986); in para 74, the ICJ observed, ‘whether the response to the [armed] attack is lawful depends on observance of the criteria of the necessity and the proportionality of the measures taken in self-defence’. 

The other reasoning which the U.S may place is anticipatory self-defence, which came into the limelight after the famous Caroline Incident (1837). If the U.S asserts anticipatory self-defence, the defence is shaky because as per Pentagon’s admission, the HAB was “traveling at an altitude well above commercial air traffic and [did] not present a military or physical threat to people on the ground.” If the U.S claims are unjustifiable, this may amount to a blatant breach of a jus cogens norm of prohibition of the use of force; wherein the U.S could incur state responsibility under international law.  At most, this incident could be a case of espionage at par with States deploying submarines conducting spying in the territorial waters. As I have argued previously, espionage per se doesn’t violate international law obligations. In a diplomatic sense, it is implied that States spy on one other. The absence of legal justification under international law can characterise the U.S action as a countermeasure. Countermeasures are justified under certain circumstances, if carried out to make other States cease the violation of international law. However, for invoking countermeasures, there are a plethora of strict requirements like a prior internationally wrongful act of the responsible State against the injured State, notification and offer to negotiate with the responsible State etc. Therefore, the purpose of countermeasure is restoration and not retributive. But the U.S. is yet to make any unambiguous statement on countermeasure. 

* Assistant Professor, The West Bengal National University of Juridical Sciences (WBNUJS). The author would like to thank Prof. (Dr.) Sandeepa Bhat B. for his valuable comments.