Guest Post: Prof Pete Pedrozo on “Military Operations in International Airspace”

Is it legal for an aircraft flying in international airspace to conduct reconnaissance operations?  Does international law permit another nation to interfere with such missions if they occur near their warships? 

There are some of the issues raised when Chinese fighters recently dropped flares in front of a Royal Australian Navy helicopter conducting surveillance operations in international airspace near a Chinese naval exercise.

Fortunately, we have Prof. Pete Pedrozo, one of the world’s top experts, to unpack this incident for us.  Since dangerous events like this one seem to be becoming more frequent, having a clear idea of the applicable law and practice is essential, so we’re grateful to have Pete’s views.

Military Operations in International Airspace 

Raul (Pete) Pedrozo

Unsafe and Unprofessional Intercept

On May 7, 2024, the Associated Press reported that a Chinese J-10 fighter had released flares 300 meters in front and 60 meters above an Australian Navy Seahawk helicopter operating in international airspace over the Yellow Sea. The Australian helicopter, which was enforcing U.N. sanctions against North Korea’s nuclear program, was forced to take evasive action to avoid being hit by the flares.

Australia protested the incident, accusing China of “unsafe and unprofessional” behavior. Had the helicopter ingested the flares into its engine, it could have caused the aircraft to ditch with potential injuries or loss of life.

China initially justified its actions claiming that the Australian helicopter flew within close range of China’s airspace in a provocative manner that endangered China’s maritime and air security. Accordingly, the Chinese fighter took the necessary measures to warn the Australian aircraft to stop its provocative behavior.

The following day, however, China changed its story, claiming that the Australian helicopter was intercepted because it was spying on a Chinese naval exercise in the Yellow Sea. After warning the Australian aircraft to cease its close-in reconnaissance, the Chinese jet took “legitimate, reasonable, professional, and safe” action to expel it, which is fully in line with international law and practice.

Even if the Australian helicopter was conducting close-in reconnaissance of a naval exercise, was China’s response is releasing flares in the aircraft’s flight path consistent with international law and practice? 

National v. International Airspace

Generally, the legality of intelligence, surveillance, and reconnaissance (ISR) operations in the air domain depends on the location of the collection platform. ISR conducted in national airspace can be restricted by the coastal State, but collection activities in international airspace are not subject to coastal State jurisdiction or interference.

Source: NWP 1-14M

Coastal States exercise sovereignty over their national airspace, which includes all airspace above their land territory, internal waters, archipelagic waters (for archipelagic States), and 12-nautical mile territorial sea (UNCLOS, arts. 2, 49; Chicago Convention, arts.1-2).

State aircraft, which includes aircraft used in military, customs, and police services (Chicago Convention, art. 3(b)), may not enter national airspace without the consent of the coastal State (Chicago Convention, art. 3(c)), and must operate with “due regard” for the safety of navigation of civil aircraft (Chicago Convention, art. 3(d)). Thus, a coastal State may prohibit ISR operations within its national airspace.

All airspace seaward of the territorial sea—i.e., over the 24-natucial mile contiguous zone, 200-nautical mile exclusive economic zone (EEZ), and high seas—is considered international airspace and is not subject to coastal State sovereignty (NWP 1-14M, §§ 1.9, 2.7.2).

Except for the production of energy from the winds, coastal State authority over the EEZ is limited to the seabed, its subsoil, and the waters superjacent to the seabed (UNCLOS, art. 56). Therefore, UNCLOS does not provide a legal basis for coastal States to assert jurisdiction over ISR (or other military) activities in international airspace seaward of the territorial sea.

Similarly, the Chicago Convention only limits military activities in national airspace (Chicago Convention, arts. 3(a), 3(c)). International Civil Aviation Organization (ICAO) rules applicable to aircraft operating in international airspace only apply to civil aircraft (Rules of the Air, annex 2). The Chicago Convention exempts State aircraft from compliance with these rules, thus allowing them to operate in international airspace free of coastal State interference (Chicago Convention, art. 3(a), Air Traffic Services, annex 11).

Efforts to designate the airspace above the EEZ as national airspace were rejected by the ICAO Legal Committee, indicating the proposal would contradict “the relevant provisions of UNCLOS which equate the EEZ … with the high seas as regards freedom of overflight.”

State Practice

During the Cold War, over forty U.S. reconnaissance aircraft were shot down in the European and Pacific regions between 1945 and 1977. These attacks were justified by the coastal State on the grounds that the aircraft had violated national airspace. The legality of ISR operations were also discussed in the Security Council following several encounters between U.S. and Soviet aircraft during the 1950s and 1960s.

During these deliberations, all sides agreed that coastal States did not have a right to interfere with intelligence collection activities in international airspace (U.N. Doc. S./P.V.680, ¶ 125) and that ISR activities directed at coastal States from international airspace were consistent with international law and the UN Charter (U.N. Doc. S./P.V.881, ¶ 64).

A more recent example is the June 2019 shootdown of an unmanned U.S. MQ-4C Triton surveillance drone by the Islamic Revolution Guards Corps (IRGC) in the Persian Gulf. The IRGC justified its actions on the grounds that the MQ-4C was collecting intelligence in Iran’s national airspace. The United States denied the Iranian allegations, indicating that the attack was unprovoked and that the MQ-4C was legally operating in international airspace.

Francis Gary Powers
Source: Wikipedia

The Security Council has also determined that peacetime ISR activities do not constitute an act of aggression under the UN Charter. In May 1960, an American U-2 spy plane piloted by Gary Powers was shot down by the Soviet Union near Sverdlovsk.

Efforts by the Soviets to have the Security Council adopt a resolution that would have labelled the U-2 surveillance flights as “acts of aggression” under the Charter were rejected by a vote of seven to two, with two abstentions (U.N. Doc. S/PV.857, ¶ 99; U.N. Doc. S/PV.860, ¶ 87).

Four months later, the Soviet Union shot down another U.S. surveillance aircraft that was operating over the Barents Sea off the Kola Peninsula. The Soviets alleged that the RB-47 aircraft was engaged only when it flew into Soviet national airspace. The United States denied the allegation, claiming that the surveillance aircraft was legally operating in international airspace (U.N. Doc. S/4384).

Soviet efforts to have the Security Council designate the U.S. surveillance flight an act of aggression once again failed by a vote of nine to two (U.N. Doc. S/PV.883 and Add.1, ¶ 187). These cases confirm that peacetime ISR activities (even in national airspace) do not violate article 2(4) of the Charter.

United Nations Convention on the Law of the Sea

A 1985 Report of the Secretary-General on the Study of the Naval Arms Race reflects a similar conclusion. After noting that UNCLOS (article 301) requires States to refrain from any threat or use of force against the territorial integrity or political independence of any State, or in any other manner inconsistent with the principles of international law embodied in the Charter, the report concludes that military activities that are consistent with the principles of international law embodied in articles 2(4) and 51 of the Charter are not prohibited by the Convention. (U.N. Doc. A/40/535, annex ¶ 188).

UNCLOS clearly distinguishes between “threat or use of force” and other military-related activities, such as intelligence collection. Article 19.2(a) repeats the language of article 301, prohibiting ships in innocent passage from engaging in “any threat or use of force against the sovereignty, territorial integrity or political independence of the coastal State.” Article 19.2(c) prohibits ships engaged in innocent passage from “collecting information to the prejudice of the defense or security of the coastal State.”

These two independent prohibitions for ships engaged in innocent passage clearly demonstrate that UNCLOS does not equate the “threat or use of force” with intelligence collection. Rather, as stated above, the test of whether ISR activities are “peaceful” is determined by article 2(4) of the Charter and other obligations under international law, including the inherent right of self-defense, reflected in article 51 (U.N. Doc. A/CONF.62/SR.67, ¶ 81).

As evidenced by State practice, the peaceful purposes provisions in the Convention only prohibit military activities in EEZs and on the high seas that threaten or use force in a manner inconsistent with the UN Charter, which the Security Council has determined does not include ISR activities.


Source: Royal Australian Navy

All States have an absolute right under both conventional and customary international law, as well as long-standing State practice, to conduct ISR operations from beyond the territorial sea and national airspace of coastal States.

Regardless of which version of the incident is true, it is clear from both Chinese narratives that the Australian helicopter was operating in international airspace when it was intercepted. In its first statement, the Chinese Foreign Ministry indicated that the helicopter was flying “within close range of China’s airspace.” In its later explanation, the Foreign Ministry stated that the helicopter was spying on a naval exercise in international waters in the Yellow Sea.

Therefore, China’s unsafe interference with the Australian aircraft in international airspace, even if it was collecting intelligence on the naval exercise, was a clear violation of international law and China’s treaty obligations under UNCLOS and the Chicago Convention.  

About the author:

Captain Raul (Pete) Pedrozo, U.S. Navy (Retired), is the Howard S. Levie Chair on the Law of Armed Conflict and professor of international law at the Stockton Center for International Law, U.S. Naval War College. Prof. Pedrozo was the former senior legal adviser at U.S. Pacific Command and served as special assistant to the Under Secretary of Defense for Policy.


The views and opinions expressed in this article are those of the author and do not necessarily reflect those of the U.S. Naval War College, the U.S. Department of Defense, or the U.S. Government.

The views expressed by guest authors do not necessarily reflect my views or those of the Center on Law, Ethics and National Security, or Duke University. (See also here).

Remember what we like to say on Lawfire®: gather the facts, examine the law, evaluate the arguments – and then decide for yourself!

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