BEIJING (Reuters) - China’s military will take action “at any cost” to foil any attempt to separate the self-ruled island of Taiwan, which Beijing claims as its own, the country’s defense minister said on Thursday.

Chinese Defence Minister Wei Fenghe salutes after addressing the Xiangshan Forum in Beijing, China October 25, 2018. REUTERS/Thomas Peter

China has been infuriated by recent U.S. sanctions on its military, one of a growing number of flashpoints in Sino-U.S. ties that include a bitter trade war, the issue of Taiwan, and China’s increasingly muscular military posture in the South China Sea.

On Monday, the United States sent two warships through the Taiwan Strait in the second such operation this year and the latest in a series of U.S. gestures in support of democratic Taiwan.

“The Taiwan issue is related to China’s sovereignty and territorial integrity and touches upon China’s core interests,” Chinese Defence Minister Wei Fenghe said at the opening of the Xiangshan Forum in Beijing, which China styles as its answer to the annual Shangri-La Dialogue security forum in Singapore.

“On this issue, it is extremely dangerous to repeatedly challenge China’s bottom line. If someone tries to separate out Taiwan, China’s military will take the necessary actions at any cost.”

Taiwan’s Presidential Office and Defence Ministry declined to comment on Wei’s remarks. Taiwan has shown no interest in being run by autocratic China.

China-Taiwan relations have deteriorated since the island’s President Tsai Ing-wen, of the independence-leaning Democratic Progressive Party, swept to power in 2016.

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Tsai says she wants to maintain the status quo with China but will not be bullied.

Beijing, which has never renounced the use of force to bring Taiwan under its control, has also viewed U.S. overtures toward the island with alarm, such as a new de facto embassy there and passage of a law to encourage visits by U.S. officials.

China’s military ties with the United States are important and sensitive, Wei said, adding that China would never give up an inch of its territory.

Beijing opposed displays of strength and provocation in the South China Sea by “nations from outside the region” carried out under the pretence of protecting freedom of flight and navigation, he added.

The world’s two largest economies needed to deepen high-level ties so as to navigate tension and rein in the risk of inadvertent conflict, U.S. Defense Secretary Jim Mattis told his Chinese counterpart in Singapore last week.

Mattis saw firsthand last month how mounting Sino-U.S. friction can undermine military contacts, when Beijing upended plans for him to meet Wei in October in Beijing at a security dialogue.

However, speaking at a monthly briefing, Chinese defense ministry spokesman Wu Qian described the Wei-Mattis talks as positive and constructive, adding that Mattis had again invited Wei to visit the United States.

China has been angered too by U.S. sanctions on its military for buying weapons from Russia.

China has also expressed concern after U.S. President Donald Trump said the United States would withdraw from a Cold War-era treaty that eliminated nuclear missiles from Europe because Russia was violating the pact.

China is not a party to that treaty, but Trump has also suggested China’s military strength played a role in his decision, which China has described as “completely wrong”.