In an island renowned for boisterous politics, Taiwan President Tsai Ing-wen is an improbable leader.

Described by those close to her as scholarly and bookish, Tsai is known for caution and understatement. In 2016, she ordered her staff to stay silent about a call with incoming President Donald Trump, even though it was the first time in decades a Taiwanese leader had spoken to a U.S. president or president-elect. (Trump was less discreet.)

When she rose to lead her party 15 years ago, she was known as a technocrat, not a transformative politician. "Many commentators view Tsai as a transitional and relatively weak leader,” a U.S. diplomatic cable assessing her place in Taiwanese politics noted at the time.