Donald Trump’s Call With Taiwan Leader Raises Fresh Uncertainty Over U.S.-China Relations

President-elect’s telephone conversation with Tsai Ing-wen breaks diplomatic protocol, angers Beijing and puts North Korea sanctions at risk

Chinese representatives are sure to seek meetings with the Trump transition team to warn that the entire relationship would be at risk if Mr. Trump pursues closer relations with Taipei.

.. A range of global issues requiring cooperation between Beijing and Washington—from management of the global economy to climate change—stand to become more complicated if Friday’s call translates into a policy shift once Mr. Trump takes office. It could also worsen existing tensions, including recent Chinese activities in the South China Sea.

.. The phone call comes only days after China backed U.N. sanctions on North Korea, the result of a monthslong, U.S.-led diplomatic effort to get Beijing on board.

The U.S. has pressed China for years to use its clout as North Korea’s biggest investor, aid donor and trade partner to persuade Pyongyang to abandon its nuclear-weapons program.The Obama administration has conveyed its view to Mr. Trump’s team that North Korea should be the top security priority for the incoming administration, according to people familiar with the conversations.

 Passage of the recent sanctions, which effectively target North Korea’s coal exports to China, had indicated Beijing’s willingness to send a message of impatience to its neighbor. Their success depends in large part on how rigorously China enforces the curbs and how well China and the U.S. continue to work together.
.. Beijing had hoped he would follow through on indications during his presidential campaign that he would downgrade U.S. alliances in Asia.
.. In 1996, it fired missiles into waters nearby, prompting the U.S. to send two aircraft carrier groups to the area.
.. Mr. Xi, as is the case with Mr. Trump, is more of a populist than his predecessors and is keen to project an image as a strong leader who is unwilling to compromise, especially on national sovereignty.
.. “One of the things Xi Jinping has made emblematic of his work style is, ‘If you do something to me, I do something to you,’”
.. “So he’ll find some way to retaliate.”
.. There is also concern in policy-making circles in Beijing and Washington that the phone call reflects the advice of several people advising Mr. Trump who have hawkish views on China and would like to see a closer U.S. relationship with Taiwan.