Regulatory Gaps Surrounding the Operation of High-Altitude Platform Stations

Introduction

International law is built on the concept of State and its sovereignty, which also includes airspace sovereignty. Airspace sovereignty has been analyzed in two separate contexts over the years. Firstly, each state has exclusive sovereignty over its airspace and complete discretion as to the admission of any overflight, and secondly, airspace above the high seas is not subject to any state’s jurisdiction, and is free to aircraft of all states.

These principles are codified under the Chicago Convention on International Civil Aviation and the Outer Space treaty. However, both of these treaties, along with other sources of international law fail to clearly define the altitude of the airspace that states have exclusive sovereignty over.

This unsettled position of law leads to regulatory loopholes, especially in terms of new and developing technologies, like High-Altitude Platform Stations (HAPS), that breach traditional airspace and aircraft definitions, but do not necessarily operate in outer space or conventional air space. These technologies, operating in “near space”, function in a legal vacuum that remains undefined. This blog aims to address this legal loophole, by analyzing real world use cases of HAPS, understanding how lack of regulation of “near space” can become a problem, and finally trying to provide a way forward for dealing with such technologies.

Definition of Airspace

It is generally accepted that a State has exclusive jurisdiction over the airspace directly above its territory, which implies that it can prohibit overflight by other states. The Chicago Convention categorically provides for complete and exclusive sovereignty of airspace for each state under Article 1.

It is, however, not clear how far the jurisdiction of states extends upwards, and this demarcation is highly disputed. This is because the Outer Space treaty provides for the exploration of Outer Space to be free for all states. The report of the Legal Subcommittee of the United Nations committee on peaceful uses of Outer Space (COPUOS), in its sixty-first session, held in Vienna from 28 March to 8 April 2022 has discussed the delimitation of Outer Space and that sovereignty does not extend to above FL600 levels, while other committees argue that sovereign airspace extends till the Karman line. The former has also been considered in the official report of the COPUOS. The Karman line is an imagined boundary where the Earth’s atmosphere ends, and it is generally accepted at 100 km over the Earth’s surface. The author argues that these two treaties are inherently incompatible until the clear demarcation is accounted for. Neither treaty expressly talks about the stratosphere, and the concepts of exclusive sovereignty of airspace and universal freedom of outer space appear to be untenable simultaneously.

None of these proposals regarding the vertical limits to state sovereignty have been accepted universally, and a commonly accepted definition is that the airspace is above the height at which an aircraft can fly. However, this is doubtful in itself since the term aircraft has not been defined in international law, and newer technologies can constantly fly at higher altitudes.

Even after the drafting of the Chicago Convention, states have taken different positions on the extent of vertical sovereignty and definitions of airspace. For example, Australia reformed its National Airspace Systems with a defined upper limit of 60,000 feet. At the same time, Australia has not expressly renounced any claim of sovereignty over 60,000 feet, other countries may interpret its activities in such manner, and claim that they are not infringing sovereignty if they deploy HAPS in Australia’s airspace. On the other hand, USSR asserted that sovereignty extended to unlimited heighted, but changed its position after Sputnik and argued that no state could claim sovereignty in space.

It is clear that the positions of state vary to a large extent, and there is no established uniform principle which can be used to define vertical boundaries of airspace sovereignty.

HAPS in the Recent Years

The author argues that existing definitions of airspace are not enough is because of newly emerging technologies like High Altitude Platform Stations. H APS, as defined by the International Telecommunication Union (ITU), are unmanned aerial vehicles that operate in the stratosphere at around 20 km and above, and have the ability to provide persistent intelligence and surveillance. They combine the flexibility of aircraft with the endurance of satellites, and are therefore different from both satellites and conventional drones.

These “near space” surveillance platforms are redefining global power projection, and have been recently recognized as a part of the top upcoming technologies by the World Economic Forum (WEF). Many countries, like United States, China, and Russia are developing this technology through companies like Airbus, AveroVironment and AVIC, because they have realized the untapped potential of the stratosphere for both civil and military purposes. There are several instances of the use of HAPS in recent years that have been reported.

Several instances of the use of HAPS in recent years have been reported. One such instance is where a Chinese balloon transversed USA airspace in early 2023 for surveillance purposes, and was shot down. Moreover, in 2023, Russia initiated a stratospheric ISR balloon for repurposing metrological balloons over sensitive zones in the Arctic and Eastern Europe. In early 2023 and 2024, Chinese surveillance balloons tracked over Taiwan airspace, which aimed to exert psychological pressure without direct military confrontation. These are only some of the instances of such technology operating in “near space”, and being utilized for ISR, research, disaster management and other important functions.

Challenges to the Operation of HAPS

HAPS is one of the front runners of technologies in 2025, and is being developed by each nation to enhance their ISR (Intelligence, Surveillance and Reconnaissance) abilities. However, new technologies also lead to regulatory loopholes that need to be addressed.

There is no regulation over the stratosphere and no universally agreed definition of airspace. Since such lack of regulation opens up scope for broad regulations, it can threaten the security and integrity of the state. Countries operating such HAPS may potentially claim that there is no right of sovereignty in the stratosphere, and that HAPS do not come under the conventional aircraft definition. If the stratosphere remains a grey area, it makes states vulnerable for a breach of sovereignty, while allowing for a defense of ambiguity.

Secondly, HAPS are dual-use technologies which eliminate the clear distinction between civil and military aircraft. It is debatable whether or not HAPS come under the regulations of the International Civil Aviation Organization (ICAO), since ICAO only regulates civil aircraft. These functions are often disguised as civilian, although, they are military in nature. The Russian transversion of Arctic and European airspace was conducted under the guise of atmospheric research. When China deployed its balloon over the American airspace, it claimed that the balloon was for civilian meteorological purposes.

This becomes important because once a country’s sovereignty is breached, it naturally will try to destroy such objects transversing its airspace. However, Article 3 bis of the Chicago convention protects civilian aircraft from unlawful uses of force. Any force employed needs to meet the tests of necessity and proportionality of exercised in the name of self-defense under customary international law as well as Article 51 of the UN Charter. When it comes to HAPS or HAPS like technology, there is no direct armed attack. Therefore, the question of whether pre-emptive self-defense is allowed under customary international law or Article 51 of the UN Charter arises, but it has to meet the tests of necessity and proportionality.

In the Caroline case, the test established that pre-emptive self-defense would be justifiable by necessity, if it was “instant, overwhelming, and left no choice of means”. Further, there must not be any alternative less intrusive measures instead of the use of force, and any such method has already been utilized. Secondly, as highlighted in the Oil Platforms case, the state can only exercise as much force as is reasonably necessary to overcome the threat, or prevent the attack from taking place. Even though the Corfu Channel case establishes that direct evidence of hostile intent is not always necessary and that intent may be inferred from circumstantial evidence, the mere deployment of HAPS is insufficient to establish any military role or hostile purpose. While HAPS may be capable of surveillance, surveillance alone does not amount to a threat of an armed attack. Consequently, the question of pre-emptive self-defense arises only where there exists a credible and imminent threat. In the case of HAPS deployment, such a threat is difficult to establish, resulting in a failure to satisfy the requirements of necessity and proportionality, as there is typically neither direct nor circumstantial evidence indicating an impending attack because they’re utilized more for surveillance purposes.

When a country is able to claim that their purpose was civil, and that they were not in a sovereign territory on the basis of legal ambiguity alone, and are therefore entitled to the protection of Article 3 Bis, it can potentially threaten security without a fail-safe. This underscores a need for regulation.

On the other hand, technologies such as HAPS need to be moderately regulated. If the stratosphere and the operation of HAPS is regulated too much, it can potentially disadvantage countries from seeking benefits out of such technologies. This can put a hindrance on innovation, along with demolishing a cost-effective measure of surveillance, real time data fusion, and sensitive region coverage. While HAPS can be deployed for military purposes and can become a threat to security of states, it can also enhance security by allowing for atmosphere and meteorological research, which will not be possible in cases of over regulation. While India has not officially deployed HAPS, it has recognized its need for border security and research, and is well underway in developing this technology.

This highlights the need to balance regulations surrounding HAPS. There are many bodies directly addressing regulations surrounding HAPS. This includes ICAO, ITU as well as the HAPS Alliance. However, there is no certainty about which regulation would govern HAPS, and recommendations and practices of existing legal bodies and bodies specifically constituted for HAPS remains to be unsatisfactory and incomplete. They either lack the jurisdiction to govern such technology, are primarily focused on the commercial aspect of HAPS or lack any binding force behind established norms.

Conclusion and the Way Forward

The contemporary nature of this technology, and its increasing use highlights the need for balanced and transparent regulation. It is understandable that it is difficult, because international law needs to cater to every country, including the countries that are under developed and cannot match such technologies. However, not regulating it puts these countries in a greater position of risk, as developed countries can potentially exploit their resources against them.

The legal status of HAPS needs to be clarified to avoid the question of airspace boundaries through a multilateral treaty of states. When only conventional aircraft operated, the silence with regards to the definition of aircraft and airspace was not a problem. But now, with such an increase in HAPS and HAPS like technologies, these criteria need to be laid down clearly.

This treaty also needs to require the clear declaration of the purpose for which such HAPS is deployed, and mandatory compliance to such purpose, along with punitive measures if a breach is therefore committed. If data is collected within the territory of another state, that country also needs to be provided with access to such data. This can help with HAPS that are genuinely employed for important purposes like the protection of health and environment. If these technologies do not follow the purpose of why they are deployed, they cannot be granted protection under Article 3 Bis. This measure can allow for a balanced approach to the operation of HAPS. In conclusion, “near space” technologies have become abundantly important in the recent years, and can be utilized for a variety of purposes. However, these purposes can also result in being exploitative to other countries and can be potentially justified in the context of broader legal ambiguities. Therefore, the author argues for an international framework to ensure the protection of each country.