The exiting president, Ma Ying-jeou, of the Nationalist Party, or Kuomintang, had pushed for closer relations with China during his eight years in office. But voters grew increasingly wary of that approach, and large protests erupted in 2014 against a trade pact with China.

Ms. Tsai has said she will maintain the cross-strait status quo, but is expected to be far more reserved than Mr. Ma in pursuing trade and other agreements with China.

Even before she was inaugurated, China showed clear indications of increasing pressure on Ms. Tsai’s incoming government.

“The honeymoon for Tsai Ing-wen is going to be very short, if it’s not already over,” said Jean-Pierre Cabestan, a professor of government and international studies at Hong Kong Baptist University.