In a highly symbolic move, U.S. Vice President Kamala Harris has become the highest-ranking American official to set foot on an island on the edge of the disputed South China Sea, a development likely to anger claimant Beijing.

As part of a three-day tour of the Philippines, Harris on Tuesday arrived on Palawan Island — the closest Philippine landmass to the hotly contested Spratly archipelago — where she delivered remarks on the importance of upholding international law and freedom of the seas, as well as on fisheries and environmental protection.

“We must stand up for principles such as respect for sovereignty and territorial integrity, unimpeded lawful commerce, the peaceful resolution of disputes and the freedom of navigation and overflight in the South China Sea, and throughout the Indo-Pacific,” Harris said in a speech aboard a Japanese-built Philippine Coast Guard vessel at Puerto Princesa, the capital of Palawan province.