The U.S. unveiled a new representative office in Taipei Tuesday, establishing a de facto embassy in the self-ruled island amid its escalating tensions with China.
There was speculation that US President Donald Trump's national security adviser John Bolton may attend the unveiling ceremony at the American Institute of Taiwan (AIT) on June 12, which would have made him one of the most senior American officials to visit Taiwan since 1979 and likely drawn China's ire.
China and the United States - now in heated talks over trade - have frequently sparred over questions of militarization of the South China Sea, where Taiwan also has competing claims to parts or all of the region. Further complicating matters, Trump broke diplomatic protocol after winning the 2016 presidential election by accepting a congratulatory telephone call from Tsai Ing-wen.
But the USA sent an assistant secretary of state for the unveiling, a visit less likely to unnerve China which was concerned that higher-level officials may attend.
In an opening address, Assistant US Secretary of State for Educational and Cultural Affairs Marie Royce, described the sprawling five-story complex, which cost $255 million to build, as much more than mere bricks and mortar.
AIT Chairman James Moriarty, Republican Congressman Gregg Harper, as well as a number of former AIT chairmen and directors also participated in the ceremony on Tuesday morning.
Chinese Foreign Ministry spokesperson Geng Shuang said Beijing was "gravely concerned" with the inauguration of the building.
China's Foreign Ministry spokesman Geng Shuang on Tuesday said it had lodged stern representations with the U.S. about the new AIT building. Trump has previously vowed to honor Beijing's One China policy, but Washington's recent attempts to cozy up to Taiwan have undermined Beijing's confidence in his pledge.
Taiwan papers have also reported that former AIT deputy director Brent Christensen would be promoted to lead Washington's diplomatic mission on the island.
The new AIT compound was constructed over nine years and has cost the U.S. some $250 million.
The widely read Chinese state-run newspaper the Global Times on Tuesday said China needed to warn Taiwan and the USA against provocation.
Beijing has also increased the frequency of military exercises in the last few months, including deploying its own aircraft carrier, the Liaoning, in the Taiwan Strait. The organization, which was first established in 1979 after the diplomatic shift, plans to officially relocate to the new facility this fall.
"I offer you this", he said, "a tangible symbol that the United States is here to stay".