In response to the cancellation of M503 routes from north to south, the US State Department expressed concerns and said that the civil aviation and safety issues of the Taiwan Strait should be resolved by both parties.

The U.S. State Department spokesman said on Thursday (February 1) to reply to the inquiry of the Taiwan joint newspaper that the United States concerned Beijing's problem of changing the route without negotiating with Taiwan, and the civil aviation and safety of the Taiwan Strait and the safety of the security of the Taiwan Strait.The dialogue between the two parties should be resolved, and it is emphasized that the United States opposes the changes in the status quo of any side on both sides of the strait, urging Beijing to stop the pressure on Taiwan's military, diplomatic and economy, and start a meaningful dialogue with Taiwan.

The Civil Aviation Administration of Mainland China announced on Tuesday (January 30) that the flight bias measures operating from north to south from north to south will be canceled from February 1, which will no longer move westward.The M503 will also be used to connect west to Fuzhou Fujian Fuzhou and Xiamen's W122 and W123 connection routes to operate from west to east to improve the operation efficiency of the aerial operation.

Since the M503 route is only 4.2 nautical miles (about 7.8 kilometers) from the Taiwan Strait midline, the Taiwan government and the academic circles are worried. This will greatly reduce the time of Taiwan ’s air defense warning.

The mainland committee of the Taiwan government shouted to the other side again on Thursday, hoping to communicate the issue of Fei'an, and at the same time, he also said that he would not see the step that needed countermeasures to propose countermeasures.