Airspace Intelligence

What is an ADIZ? (And Why Flying Into It Is Not an Invasion)

By Taiwan Strait Tracker Intelligence Team | February 2026

If you rely on mainstream news alerts, you might believe Taiwan's sovereign airspace is invaded on a weekly basis. In reality, the airspace remains untouched. The confusion stems from a fundamental misunderstanding of what an Air Defence Identification Zone actually is.

To accurately assess geopolitical risk, our intelligence team relies on precise legal and geographic definitions. The most commonly abused acronym in Indo Pacific reporting is "ADIZ." When media outlets conflate an ADIZ with sovereign airspace, they manufacture panic. Here is the operational difference, and why we track it the way we do.

Sovereign Airspace vs The Buffer Zone

International law, governed by the Chicago Convention, is very clear about where a country's actual airspace ends. Sovereign airspace extends exactly 12 nautical miles from a nation's coastline. If a foreign military aircraft breaches that 12 mile limit without permission, it is an illegal invasion and a direct act of war.

An Air Defence Identification Zone (ADIZ) is something entirely different:

• It is not international law: An ADIZ is a unilateral declaration with no backing in international treaties.
• It is over international waters: It acts as an early warning buffer zone extending hundreds of miles beyond sovereign territory.
• The purpose: It gives a nation time to identify approaching aircraft and scramble interceptors long before the 12 mile boundary is threatened.

The Legacy of the Cold War

The concept of the ADIZ was invented by the United States in 1950. Today, over 20 countries operate their own zones, including Japan, South Korea, and China.

Because these zones are unilaterally declared, they frequently overlap. Taiwan's ADIZ, established by the US military in the 1950s, geographically covers large portions of mainland China. This creates a bizarre reality: a People's Liberation Army (PLA) fighter jet taking off from a domestic runway in China is technically "entering" Taiwan's ADIZ the moment its wheels leave the ground.