By Kristen Tieman

On Saturday, January 28, 2023, a two-hundred-foot-tall balloon[1] covertly entered US airspace over Alaska.[2]  Five days later, on February 2, news of the balloon made national headlines as it was spotted over the continental United States.[3]  Immediately, questions began to arise: What were China’s intentions with the balloon?  Why would China use a balloon as a surveillance device, rather than a satellite?  Should the US military shoot the balloon out of the sky?  Although many questions remain unanswered, one thing is clear: China violated international law by sending the unauthorized spy balloon into US airspace.

During the media frenzy covering the movement of the balloon across the continental United States, a Pentagon spokesperson noted that “the balloon has violated US airspace and international law.”[4]  But what laws did it break?

Near the end of the Second World War, fifty-four nations signed the Convention on International Civil Aviation, more commonly known as the Chicago Convention.[5]  The Chicago Convention “established the core principles permitting international transport by air, and led to the creation of the . . .  International Civil Aviation Organization (ICAO).”[6]  The goal of the ICAO is to “organize and support the intensive international cooperation which the fledging global air transport network would require.”[7]

Since its inception nearly eighty years ago, the ICAO has grown to encompass 193 countries.[8]  The ICAO adopts aviation standards and relies on the cooperation of its Member States to ensure uniformity.[9]  The United States and China are among the Member States, and as such, both are expected to follow the guidelines established by the ICAO.[10]

The Chicago Convention instructs that “every State has complete and exclusive sovereignty over the airspace above its territory.”[11]  Further, “no state aircraft . . .  shall fly over the territory of another State . . . without authorization by special agreement or otherwise.”[12]  State aircraft is considered “aircraft used in military, customs, and police services.”[13]  The ICAO also sets out guidelines for “unmanned free balloons.”[14]  Such balloons, other than those “used exclusively for meteorological purposes” are prohibited from entering foreign airspace unless directly authorized by the foreign state.[15]  Each country is free to set its own policies for authorization of foreign aircraft, including balloons.

Under US law, “aircraft of the armed forces of a foreign country” may only enter US airspace if authorized by the Secretary of State.[16]  Foreign governments must comply with a number of procedures to receive such authorization.[17]  At least three days before the foreign aircraft enters US airspace, the foreign government must receive a Diplomatic Clearance Number (DCN) by the Department of State.[18]  The procedure for receiving a DCN includes filing an online application, which must be approved by Diplomatic Clearance Officer.[19]  The Chinese balloon did not have the clearance necessary to fly in US airspace.[20]

Approximately one week after the balloon was first spotted over US territory, it was shot down by the US military off the coast of South Carolina.[21]  Although some lawmakers called on President Biden to shoot down the balloon earlier in its path, the President ultimately decided to wait until the balloon was off the cost of the United States in an attempt to prevent danger to humans and property.[22]  For China, who has maintained that the balloon was merely a civil aircraft used for meteorological purposes, the US military’s show of force in striking down the balloon was a serious “overreaction.”[23]  China sees the move as an escalation in the growing tensions between the two countries.[24]  In contrast, the US has declared that the balloon was a state-sponsored aircraft with surveillance capabilities, thus justifying a strong use of force to eliminate the threat to US sovereignty.[25]

If the balloon were truly of a civil nature and acting lawfully, as China claims, then the US may have been unjustified in its actions.  For civil aircraft violating a foreign nation’s sovereignty, the ICAO instructs that the foreign nation may “require the landing at some designated airport . . .  [or] may also give such an aircraft any other instructions to put an end to such violations.”[26]  This section means that “a state may still use force against a civil aircraft acting illegally, provided that such action does not endanger the latter’s integrity.”[27]  Thus, if the Chinese balloon were civil in nature and acting legally, the US was likely not justified in shooting down and destroying the balloon.

However, the US stands by its position that the balloon was a state-sponsored surveillance device.[28]  State-sponsored aircraft are subject to stricter guidelines than civil aircraft.[29]  If the US is correct in its classification of the balloon, then it was justified in using military force to shoot down the balloon.[30]

Clearly, many questions still remain regarding the balloon’s purpose, surveillance capacity, and implications on US-China relations. Hopefully, over the coming weeks, more information will be brought to light to clarify the mysterious circumstances surrounding the balloon.

[1] Dan De Luce & Dareh Gregorian, Downed Chinese balloon was 200 feet tall, U.S. military says, NBC News (Feb. 6, 2023, 4:48 PM),

[2] Lara Seligman & Sam Stein, Timeline: A Chinese spy balloon’s trip across the United States, Politico (Feb. 5, 2023, 10:02 AM),

[3] Helene Cooper & Edward Wong, China’s spy balloon drifted for 7 days across the U.S.: A Timeline, N.Y. Times (Feb. 4, 2023),

[4] David Vergun, General Says Chinese Surveillance Balloon Now Over Center of U.S., U.S. Dep’t of Def. (Feb. 3, 2023),

[5] The History of ICAO and the Chicago Convention, ICAO,

[6] Id.

[7] Id.

[8] About ICAO, ICAO,

[9] Id.

[10] Member States, ICAO,

[11] Convention on International Civil Aviation part I, ch. I, art. 1, 2006.

[12] Id. at art. 3(c).

[13] Id. at art. 3(b).

[14] International Standards: Rules of the Air app. 4-1, July 2005.

[15] Id. at 2.2.

[16] 49 U.S.C. § 40103(d).

[17] Bureau of Political-Military Affairs, Diplomatic Aircraft Clearance Procedure for Foreign State Aircraft to Operate in United States National Airspace, U.S. Dep’t of State (Dec. 14, 2022),

[18] Id.

[19] Id.

[20] Charlie Dunlap, Guest Post: “The Chinese balloon shoot-down incident and the law: some observations”, Duke Lawfire (Feb. 5, 2023),

[21] Seligman & Stein, supra note 2.

[22] Id.

[23] Verna Yu & Julian Borger, War of words over downed Chinese spy balloon continues as US recovers debris, The Guardian (Feb. 6, 2023, 6:44 PM),

[24] Id.

[25] Seligman & Stein, supra note 2.

[26] Maj Anne de Luca, Using the Air Force against Civil Aircraft: From Air Terrorism to Self-Defense, ASPJ Africa & Francophonie 3d. Q. (2012), at 49.

[27] Id.

[28] Seligman & Stein, supra note 2.

[29] Kuan-Wei Chen, China violated international laws and standards with its surveillance balloon, The Conversation (Feb. 9, 2023, 1:30 PM),

[30] Id.