Asia Fact Check Lab: Did the U.S. balloon strike violate international norms?

By Dong Zhe and Shi Shan
Asia Fact Check Lab: Did the U.S. balloon strike violate international norms?
Photo: RFA

In Brief

A Chinese high-altitude balloon entered U.S. airspace on Jan. 31 and was shot down by a U.S. F-22 fighter jet on Feb. 4. China's Ministry of National Defense claimed the U.S. response was "an obvious overreaction.” China’s Foreign Ministry said the action “violated international norms and the spirit of international law.”

Asia Fact Check Lab (AFCL) found that China acknowledged the balloon’s presence in U.S. airspace only after American officials inquired about its presence, disregarding the common international practice to immediately notify a country whose airspace has been inadvertently breached. China claimed its airship was designed for meteorological research that had been blown off course. The U.S. decision to shoot down the balloon in its own airspace is an exercise of sovereignty in line with international law, AFCL has found.

In Depth

What are the relevant laws concerning foreign aircraft entry into U.S. airspace?

Article 8 of the Convention on International Civil Aviation, a U.N. treaty signed by over 190 countries including the United States and China that establishes rules for international air travel, states that no unmanned aircraft shall fly over the territory of any country without first being granted permission. 

Did China notify the U.S. of this unmanned airship before it entered U.S. airspace?

The United States notified China its balloon had penetrated U.S. airspace after it passed north of Alaska's Aleutian Islands on Jan. 28, the Pentagon said at a Feb. 4 press conference. The balloon entered Canadian airspace on Jan. 30 and then flew back into the U.S. on Jan. 31. China publicly commented on the balloon only after being notified by the U.S. 

“The United States government has detected and is tracking a high-altitude surveillance balloon that is over the continental United States right now, ” Brig. Gen. Patrick S. Ryder, the Pentagon spokesman, said at a press conference on Feb. 2. Ryder said that American officials had notified China of the intrusion through various channels.

Did the U.S. violate international norms by shooting down the balloon?

International law does not define the upper limit of a country’s airspace. One commonly used international definition is the Kármán line, a theoretical boundary between earth’s atmosphere and outer space 100 kilometers (62 miles) above mean sea level. In the United States, the military and NASA set 50 miles (80 km) above land as the point where space begins. The unmanned Chinese airship which flew into the continental U.S. at an altitude of 59,000 feet (11.2 miles, or 18 km) fell well within the range of national airspace under either boundary. 

An F-22 fighter jet shot down the Chinese balloon over U.S. territorial waters on Feb. 4. The recovered balloon debris is being analyzed by the FBI. Chinese Defense Ministry spokesman Tan Kefei called the U.S. response "an obvious overreaction." Xie Feng, China’s vice minister of Foreign Affairs, said that the civilian balloon’s intrusion of U.S. airspace was a chance occurrence outside China’s control and therefore a legal instance of force majeure. “The U.S. use of force against a Chinese civilian airship about to leave U.S. airspace seriously violates both the spirit of international law and common international practice,” Xie said. 

Julian Ku, a professor at Hofstra University in New York who researches international dispute resolution and criminal law, said in an interview with AFCL that “shooting down a balloon in U.S. airspace does not violate any international law.” Ku said that there are few international restrictions on the use of force against unmanned aircraft that violate a sovereign country’s airspace. When Iran shot down a U.S. drone flying over Iranian territory in 2011, the United States did not claim that the action violated international law or practice.

Ku argued if the balloon had been manned by a crew, the decision to shoot it down might have violated the principle of proportionality, a prohibition in the Geneva Conventions against indiscriminate military attacks that cause undue loss of civilian life. However, shooting down an unmanned airship suspected of espionage while flying over U.S. airspace without permission is justifiable, Ku said. 


The Convention on International Civil Aviation grants every country jurisdiction over foreign aircraft flying within its airspace. All foreign governments need to apply for planned passage of these vessels in advance and notify affected countries if one enters another country’s airspace by mistake. All available evidence suggests that China only acknowledged the existence of the balloon after being confronted by American officials.

China’s allegation that the U.S. decision to shoot down the balloon violated international norms also does not hold up to scrutiny. International law does not define what constitutes excessive force against unmanned aircraft that violate a country’s airspace. 

Asia Fact Check Lab (AFCL) is a new branch of RFA, established to counter disinformation in today’s complex media environment. Our journalists publish both daily and special reports that aim to sharpen and deepen our readers’ understanding of public issues.


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