The White House warned that it intends to prevent China from taking over territory in international waters in the South China Sea by building islands out of reefs and then using them for defensive purposes.
But China is warning that any effort to stop its island-building campaign would require the United States to "wage war."
White House spokesman Sean Spicer on January 23 repeated comments that Secretary of State nominee Rex Tillerson made earlier this month, saying that China should not be allowed access to islands it has built in contested areas of the South China Sea.
"If those islands are in fact in international waters and not part of China proper, then yeah, we're going to make sure that we defend international territories from being taken over by one country," Spicer said.
Tillerson at confirmation hearings had said "we're going to have to send China a clear signal that, first, the island-building stops and, second, your access to those islands also is not going to be allowed."
Tillerson's remarks suggested the possibility of a U.S. naval blockade around the islands, which prompted Chinese state media to warn that the United States would have to "wage war" to carry out its plan.
Based on reporting by AFP and Reuters