Taiwan President Tsai Ing-wen left for the United States on Thursday on a trip that has angered Beijing, and, in a veiled reference to China, warned democracy must be defended and that the island faces threats from "overseas forces."

China, which claims self-ruled and democratic Taiwan as its own and views it as a wayward province, has called on the United States not to allow Tsai to transit there on her overseas tour.

She is spending four nights in the United States in total, two on the way there and two on the way back on a visit to four Caribbean allies. Tsai will go to New York on her way there, and then is expected to stop in Denver on the way back.