BEIJING/TAIPEI -- A U.S. naval warship sailed through the Taiwan Strait in an apparent show of support for Taiwanese President Tsai Ing-wen, the Beijing-skeptic who won reelection just days earlier.
Taiwan's Ministry of National Defense announced Friday that it spotted the U.S. vessel sailing north through the strait on Thursday. China's Ministry of Foreign Affairs spokesman, Geng Shuang, told reporters the same day that China monitored the warship as well.
"The Taiwan question is the most important and most sensitive issue in China-U.S. relations as it bears on China's sovereignty and territorial integrity," Geng said.
After reiterating the One China principle, under which Beijing insists that Taiwan is an inalienable part of a single China that will be reunified one day, Geng urged the U.S. to "avoid harming China-U.S. relations and affecting peace and stability across the Taiwan Strait."
The timing of the transit seems to send a message that U.S. President Donald Trump and his administration will back Tsai, who does not accept the One China principle.
Tsai and Beijing officials have recently engaged in a war of words surrounding this issue.
"We don't have a need to declare ourselves an independent state," Tsai told the BBC this week. "We are an independent country already and we call ourselves the Republic of China, Taiwan."
Tsai took a hard line against the prospect of armed intervention by the Chinese military. "Invading Taiwan is something that is going to be very costly for China," she said.
The spokesperson for China's Taiwan Affairs Office, Ma Xiaoguang, pushed back furiously against Tsai's comments Wednesday, insisting that Taiwan is not a sovereign state.
Taiwan "is a sacred and inalienable part of China," Ma said.
Taiwan's defense ministry appears to have taken the initiative to announce the passage of the U.S. warship as a way to emphasize island's ties with the U.S. amid mounting military pressure from China.
Thursday's transit through the Taiwan Strait is the first by the U.S. Navy this year following November's pass-through by a missile cruiser. China responded almost immediately by sailing a naval fleet through the strait, including the first domestically made aircraft carrier.
The latest development comes after the U.S. and China signed the first phase of a trade agreement on Wednesday. Despite the thaw on the trade front, tensions remain high in security matters.