Defense Secretary Mark Esper and his Chinese counterpart lectured one another in a 90-minute call as the highest level U.S. delegation in four decades plans a provocative visit to Taiwan.
China claims sovereignty over the vast majority of the economically important body of water, and in recent years, it has built artificial islands to bolster those claims.
China's leader seeks to bring an old U.S. ally into his sphere. But the Philipine people are sceptical that China will deliver on its promise of billions of dollars in aid.
The USS Carl Vinson, a nuclear-powered carrier, is expected to spend four days at the port of Danang at a time of tensions over China's expansion in the South China Sea.
The British Navy only just began rolling out the largest warship it has ever built, but it already has an eventual mission in mind for the aircraft carrier and its sister ship: the South China Sea.
In the past week, China has pressed its territorial claims in the South and East China seas, opening a cinema on a disputed island and intercepting a U.S. surveillance plane in an "unsafe" encounter.
The narrative last week was that the U.S. and its allies in the western Pacific were gearing up to confront North Korea. But a strike group that was reportedly on its way isn't anywhere near there.