Taiwan President Tsai Ing-wen speaks during a memorial service for the late former Taiwanese President Lee Teng-hui in Taipei, Taiwan on Saturday, Sept. 19, 2020.
On Saturday, Beijing dispatched 19 more warplanes, two of which were bombers, according to Taiwan's Defense Ministry.
Lee had built a separate Taiwanese political identity, distinct from mainland China, which claims Taiwan as part of its own territory to be reunited by force if necessary.
The Trump administration has taken multiple steps in recent months to strengthen its engagement with Taiwan, angering China.
Krach is the second high-level official to visit Taiwan in two months, following U.S. Health Secretary Alex Azar in August.