The U.S. government on Tuesday held a dedication ceremony for Washington's new de facto embassy in Taiwan, with which it maintains substantial but non-official ties.

Assistant Secretary of State for Educational and Cultural Affairs Marie Royce, leading the U.S. delegation, called the massive complex "a symbol of the strength and vibrancy of the U.S.-Taiwan partnership in the 21st century."

The new office of the American Institute in Taiwan, located in Taipei's Neihu district, cost $250 million and took nine years to complete.

Royce is the highest level official of the U.S. Department of State to visit Taiwan since 2015.

She is also one of just a few U.S. officials to visit Taiwan after U.S. President Donald Trump signed into law the Taiwan Travel Act championed by Royce's husband, Rep. Ed Royce of California. The act encourages U.S. and Taiwan officials of all levels to visit each other.

In her address, Taiwan President Tsai Ing-wen lauded the new building as "a new chapter in a story that has been decades in the making."

While there earlier was speculation that a Cabinet-level official would be dispatched to the ceremony from Washington, doing so would most likely have angered Beijing, which regards the island as part of its territory.

China has urged the United States to avoid having official contacts with Taiwan or improving relations in substantive ways.

Outgoing AIT Director Kin Moy described the American delegation as "perfect" for the occasion, saying the officials represented all of the cooperative areas between United States and Taiwan.

In addition to Royce, U.S. Rep. Gregg Harper, AIT Chairman James Moriarty and others also attended event.

Moriarty emphasized that "the cultural relationship" and "people-to-people relationship" between Taiwan and the United States are "the strongest."

In Beijing, a Chinese Foreign Ministry spokesman later Tuesday expressed "grave concern" over the U.S. government's decision to send a senior official to attend the AIT ceremony, saying it violated the one-China principle and interfered in China's domestic affairs.

The spokesman also urged Washington to "correct the wrong" to avoid undermining Sino-U.S. relations and destabilize the Taiwan Strait.