Nauru resumes diplomatic relations with China

China and the Pacific Island nation of Nauru signed a joint communique on the resumption of diplomatic relations. Nauru's move reduces the number of so-called "diplomatic allies" of the Taiwan region to only a dozen. Including Nauru, 10 countries have cut formal relations with Taiwan over the past 8 years. The U.S. however, expressed isappointment over Nauru's choice. Why is that?