A two-star navy admiral overseeing U.S. military intelligence in the Asia-Pacific region has made an unannounced visit to Taiwan, two sources said Sunday, in a high-level trip that could vex China.

The sources, who include a Taiwanese official familiar with the situation, said the official was Rear Adm. Michael Studeman. The sources spoke on condition of anonymity.

According to the navy's website, Studeman is director of the J2, which oversees intelligence, at the U.S. military's Indo-Pacific Command.