"On the South China Sea, China cannot be allowed to use its artificial islands to coerce its neighbors or limit freedom of navigation or overflight," Branstad stated, according to his prepared remarks.
US Secretary of State Rex Tillerson is expected to discuss the situation in the South China Sea during a meeting with his Association of Southeast Asian Nations (ASEAN) counterparts on May 4.
The South China Sea is the site of several territorial disputes between a number of countries, including China, Vietnam and the Philippines.
In July 2016, an international tribunal in The Hague ruled in favor of the Philippines after it challenged China’s claims of sovereignty in the South China Sea. China has not recognized the tribunal’s ruling.