"We’ll continue that [military exercises]," Mattis said on Tuesday. "There’s only one country that seems to take active steps to rebuff them or state their resentment of them. But it's international waters, and a lot of nations want to see freedom of navigation."
The US-Chinese standoff in the South China Sea takes place amid the ongoing disagreements on external trade between the two states.
In 2016, an international tribunal in The Hague ruled that Beijing's claims to sovereignty over South China Sea waters had no legal basis. China denied the court ruling and argued that the tribunal had no jurisdiction in the case.
Earlier this month, White House announced that the United States had spoken directly to China about continued militarization in the South China Sea, promising short- and long-term consequences.