Taiwan’s President Tsai Ing-wen

:: China urged the US on Friday not to permit Taiwan’s president to travel through US territory en route to the island’s diplomatic allies in the Pacific, a sensitive visit shortly ahead of US President Donald Trump’s trip to Beijing.

China considers democratic Taiwan to be a wayward province ineligible for state-to-state relations and has never renounced the use of force to bring the island under its control.

China regularly calls Taiwan the most sensitive and important issue between it and the US, and Beijing always complains to Washington about transit stops by Taiwanese presidents.

President Tsai Ing-wen departs on Saturday on a week-long trip to three Pacific island allies — Tuvalu, the Solomon Islands and the Marshall Islands — transiting via Honolulu and Guam.

It comes less than two weeks before Trump is due to visit China. Trump angered Beijing last December by taking a telephone call from Tsai shortly after he won the presidential election.

China has made “stern representations” to the US over the matter, said Foreign Ministry spokesman Geng Shuang, urging the US to strictly abide by the “one China” policy.

China hopes the US does “not allow her to transit, not send any wrong signals to Taiwan independence forces and take real actions to protect the overall picture of China-US relations and peace and stability in the Taiwan Strait,” Geng told a news briefing.

The trip to the US will be Tsai’s second this year. In January she stopped over in Houston and San Francisco on her way to and from Latin America, visiting the headquarters of micro-messaging service Twitter, which is blocked in China, while in California.

In Houston, she met Republican US Senator Ted Cruz and Texas Governor Greg Abbott. She also spoke by telephone with US senator John McCain, head of the powerful Senate Committee on Armed Services.

China suspects Tsai wants to push for the formal independence of Taiwan, a red line for Beijing. Tsai says she wants to maintain peace with China, but will defend Taiwan’s democracy and security.

China has heaped pressure on Taiwan since Tsai took office last year, suspending a regular dialogue mechanism and slowly peeling away its few remaining diplomatic allies.

Just 20 countries now maintain formal ties with Taiwan, mostly small states in Central America, the Caribbean and the Pacific.

The US has no formal ties with Taiwan, but is bound by law to help it defend itself and is the island’s main source of arms.

Tsai’s call with Trump was the first between US and Taiwan leaders since President Jimmy Carter switched diplomatic recognition to China from Taiwan in 1979.