Tensions in Taiwan are increasing. More than a hundred Chinese warplanes and seven warships have been spotted near the island in the past 48 hours, increasing pressure on Taiwanese authorities. The latter strongly condemned on Monday September 18 “provocative actions” that led to “an increase in tensions and a deterioration in regional security.”
Although Taiwan has never officially declared independence, it enjoys de facto military, political and diplomatic autonomy. An increasingly unbearable situation for Beijing, which sees the island as a rebel province that should be annexed to the country – including by force. The increase in the annual number of incursions by Chinese military aircraft reflects this hardening: 380 in 2020, 960 in 2021, 1,727 in 2022.
China’s latest show of force involved massive crossings of fictitious lines known as the Air Defense Identification Zone (Adiz) and the “center line.” Key concepts of Taiwanese sovereignty, now at the heart of the latent conflict between Beijing and Taipei.
What are the differences between the ADIZ, the median line and the national airspace?
National airspace is the area extending up to 12 nautical miles, or approximately 22 kilometers, around a country’s coastline. States have full sovereignty over their respective airspace.
The Air Defense Identification Zone (Adiz) extends beyond this sovereign airspace. It acts as a buffer zone where a country’s authorities can detect the passage of potentially enemy aircraft, giving themselves time to respond to a possible intrusion. Taiwan’s Adiz covers a large area around the main island, extending across the entire strait and even part of the Chinese coast.
The “center line” refers to the imaginary line equidistant from the coasts of China and the island of Taiwan. It forms a kind of unofficial border between the two opponents, which are separated by the Formosa Strait, which is between 130 and 180 kilometers wide.
“Only national airspace is recognized as a concept of international law,” recalls Professor Alessio Patalano, a specialist in maritime strategy in East Asia at King’s College London. “The establishment of an Adiz is a political decision, usually recognized by states, to create a space between two countries for the precise purpose of protecting themselves and managing de-escalation.”
The recent incursions by Chinese aircraft therefore allow Beijing to increase pressure on the Taiwanese authorities without formally violating international law.
What red line is not allowed for Chinese aircraft to cross?
The Taiwanese have not openly drawn a “red line,” declaring, for example, that they would automatically shoot down any Chinese aircraft that exceeded a certain threshold. An ambiguous position that allows Taipei to retain some freedom of action in response. “Putting a red line can invite the opponent to test it, so it is not ideal to do it,” emphasizes Alessio Patalano.
With Chinese aircraft now regularly crossing Adiz and the Central Line, the logical next step for Beijing would be to test incursions into Taiwan’s national airspace, that is, less than 12 nautical miles (22 kilometers) from the island’s coast.
“We can then imagine that the Taiwanese would then react as they are doing now, by activating anti-aircraft defenses and sending their fighters to intercept the Chinese aircraft and escort them out of their airspace,” says Alessio Patalano.
The response of the United States and the international community would be critical in this regard.
“So far the incursions have not violated international law, so there is still room for maneuver. “On the other hand, if Chinese aircraft penetrate within 12 nautical miles, that requires a much more complicated political argument,” the expert adds. The lack of response from the international community would confirm the assumption that Taipei no longer has sovereignty over its territorial waters.
What are the effects of these repeated attacks?
At the political level, it is a way for Beijing to assert its sovereignty and override the concept of a median line and therefore a border with Taiwan.
“Crossing the Adiz or middle line is already allowing Beijing to create a problem for the Taiwanese, the United States and the rest of the international community, who want to avoid normalizing behavior that no longer respects the practice established since the 1960s “, deciphers Alessio Patalano.
On a military level, these repeated incursions allow Taiwan’s air defenses to be worn down without firing a shot. If F-16 fighter jets take off much more frequently to conduct intercepts, Taipei will incur significant operational costs. Aside from the direct impact of additional flying hours on the budget, Taiwanese aviation is facing an overload of spare parts and crews.
Finally, the frequency of these raids increases the risk of a collision between Chinese and Taiwanese aircraft, which could trigger an uncontrollable crisis.
Could these incursions serve as a cover for a military attack? Taiwan ?
Conducting training maneuvers is a great classic of military strategy – as we saw before the invasion of Ukraine in February 2022.
But the Chinese forces deployed in recent incursions are far from sufficient to consider a frontal attack on Taiwan. According to military experts, the invasion of Taiwan would require a significantly higher concentration of troops to cross the Formosa Strait.
“In the maritime context we must, above all, take into account the cumulative nature. Previously we had never seen more than 40 aircraft cross the center line. Next time there will be maybe 50 planes… If it continues to increase, it will make it more difficult to determine the nature of these operations: simple intimidation or the prelude to a real attack,” says Alessio Patalano.
Not enough to provide a strategic surprise, but enough to gain a few valuable hours in the event of open conflict.