The United States has also stepped in, saying it opposes such unilateral changes by China, according to Taiwanese media. In response to a question from Taiwan’s government-run Central News Agency, Brian Hook, a policy adviser to Secretary of State Rex W. Tillerson, said China should have consulted with Taiwan first.
Tensions between Taiwan and China force the United States to engage in a difficult geopolitical balancing act. While Washington has joined most of the rest of the world in keeping Taiwan at diplomatic arm’s length for fear of angering China, it also obligated by treaty to provide the means for the island to defend itself.
According to Taiwanese media reports, Taiwan has asked friendly nations to raise concerns about the new route with the International Civil Aviation Organization, the U.N. body that oversees international air routes. Taiwan cannot directly appeal to the organization because it is not a member of the United Nations. Taiwan also has no formal ties with the aviation body itself, which is headed by Fang Liu, a Chinese citizen who since 2016 has denied Taiwan observer status.
The establishment of the new air route comes as China has been stepping up efforts to isolate Taiwan, which broke away when the Communist Party took control of China in 1949. Earlier this month, Chinese authorities forced big multinational corporations that do business in China, including the Marriott hotel chain and Delta Air Lines, to remove Taiwan from lists of countries on their websites.
China began raising the pressure on Taiwan after Ms. Tsai’s election in 2016. The government of President Xi Jinping of China cut off official communications channels, citing her unwillingness to subscribe to the notion that Taiwan belongs to “one China.” Mr. Xi, who has pledged to restore China to international greatness, has issued stern warnings to Taiwan, saying China will never relinquish control of any part of its territory, even though the Communist government has never ruled Taiwan.
In a New Year’s statement last month, Zhang Zhijun, minister of China’s Taiwan Affairs Office, put blame for the current tensions on the Tsai administration, accusing it of “indulging and conniving with ‘Taiwan independence’ forces pushing forward with ‘desinification’, ‘progressive Taiwan independence’ and all kinds of backwards policies.”
The failure to consult with Taiwan before establishing the air route is seen as a slap in the face aimed at Ms. Tsai. In 2015, when Taiwan was governed by the more China-friendly administration of Ms. Tsai’s predecessor, Ma Ying-jeou, Beijing and Taipei negotiated an agreement for China to use a similar air route over the Taiwan Strait for Chinese airliners flying the opposite direction, from north to south.
In a statement on Wednesday, China’s Taiwan Affairs Office said the route was an internal affair of China. It also said that the safe use of the earlier, 2015 route proved that there was no safety risk in flights in the Taiwan Strait.
The use of airliners also follows a Chinese strategy of relying on nonmilitary means to assert its sovereignty in other disputes in the region while avoiding a full-blown, armed confrontation.
China has dispatched coast guard vessels to challenge Japanese control of islands in the East China Sea that China also claims. In the South China Sea, China has used commercial fishing boats and ships from its fisheries management agency to demonstrate its presence in areas also claimed by Southeast Asian nations.
Taiwan also has a history of viewing Chinese airliners as a Trojan horse for military threats against the island. Up until the early 2000s, Taiwan resisted opening direct flights by commercial airliners between China and Taiwan partly out of fear that Chinese military aircraft could evade radar detection by sneaking in behind civilian jets.
Taiwanese officials and security experts said that they think China is growing bolder as its People’s Liberation Army has narrowed the military imbalance with the United States. China’s move “has caused a lot of concern and discussion on our side,” said a Taiwanese government official speaking on condition of anonymity because of the sensitivity of the subject. He also praised the United States for speaking out against China’s move.
The new air route has alarmed some security experts because it increases China’s ability to launch a surprise attack on the Taiwanese island groups of Kinmen and Matsu, which are near the Chinese coast and thus on the front line of Taiwan’s defense, by allowing Chinese aircraft to get closer before they can be detected.
By making it easier for China to launch a first strike, the new air route risked further destabilizing an already tense region, said Ian Easton, a research fellow at the Project 2049 Institute, an Arlington, Va.-based think tank, who has done research on Chinese war plans for Taiwan.
“Given the close-in nature of the standoff, early warning time is vital for stability,” he said, “and it’s being further constricted.”