epa06416066 A passenger jet of Taiwan's China Airlines takes off from the Taipei Songshan airport in Taipei, Taiwan, 04 January 2018. According to media reports, on 04 January 2018 Taiwan protested China's four flight routes in the Taiwan Strait which theaten the safety of international flights. The four routes are M503, which is close to the center line in the Taiwan Strait plus routes W121, W122 and W123 which interfere with Taiwanese flights from Taiwan proper to Taiwan-held islets of Kinmen and Matsu off China's Fujian Province. 'China's unilaterally launching these four routes on the same day endagers safety of international flights. We urge China to immediately stop using these flight routes and hold consultations with Taiwan. If China goes ahead with the plan, it has to bear grave consequences on cross-Strait ties,' Mainland Affairs Council Minister Catherine Chang told a news conference. China proposed the new flights routes in 2015, saying it was necessary to burden on exicisting routes and cut flight delays caused by the surge in air China's air traffic. After Taiwan protested, Beijing only partially used flight route M503 for north-to-south direction flights. But on 04 January, the Civil Aviation Administration of China said it will start fully using M503, also allowing south-to-north dirction flights, as well as launching the three feeder routes off the coast of Fujian. China's fully use of flight route M503 threatens Taiwan's security because it will allow Chinese planes to fly closer to the center line in the Taiwan Strait and it will take them a few minutes to enter Taiwan's air space. EPA/DAVID CHANG