TAIPEI (Taiwan News) — The Mainland Affairs Council on Sunday slammed China for unilaterally announcing the activation of the W121 connecting path along the M503 flight route.

MAC criticized the move as a disregard for past cross-strait understandings and Taiwanese public opinion, increasing regional instability, per CNA. The council said that there was no legitimate reason to open the route.

The council said that both sides had reached a consensus in 2015 regarding the operation of the M503 route and its three connecting routes, W121, W122, and W123. The M503 flight path was agreed to be southbound only and shifted six nautical miles (11 km) westward, while activation of the connecting routes would require bilateral communication.

It pointed out that this is the third time Beijing has unilaterally violated the consensus. The council said the decision was regrettable and urged China to resume talks as soon as possible through existing mechanisms.

China’s Civil Aviation Administration announced at 8:59 a.m. on Sunday that starting immediately, it would activate the W121 connecting route along the M503 to "further optimize the airspace environment and enhance operational efficiency."

Taiwan Affairs Office Spokesperson Chen Binhua (陳斌華) said the move is aimed at alleviating increased air traffic pressure in the region, ensuring flight safety, reducing delays, and safeguarding passenger rights, claiming it is "beneficial for (people) on both sides of the Taiwan Strait."

However, the MAC countered that China's international air passenger traffic has yet to return to pre-COVID levels, and W121 is not part of any cross-strait flight route. "How can it be said that this facilitates cross-strait personnel exchanges?" the MAC said.

The council said that given the current complex cross-strait and Asia-Pacific situation, such unilateral actions by China risk escalating regional tensions, which is in no party's interest. It urged Beijing to halt such moves.

Controversy over the M503 route has persisted since 2015, when China unilaterally designated it. The path runs close to the median line of the Taiwan Strait, raising concerns over national security and aviation safety.

On Jan. 30, 2024, China’s Civil Aviation Administration announced it would cancel the north-to-south "offset measure" on the M503 route starting Feb. 1. This meant that Chinese flights flying southbound over the Taiwan Strait would come closer to the edge of the median line, Taiwan's FIR, and ADIZ.

In addition, China also enabled W122 and W123 routes to run eastward to "improve the efficiency of airspace operations." These routes link route M503 with the Chinese cities of Fuzhou and Xiamen.