American diplomats left their consulate in the Chinese city of Chengdu, after a 72-hour deadline expired.
China ordered the closure in response to the US ordering the Chinese to close its consulate in Houston, Texas, last week.
Before Monday’s deadline, staff were seen leaving the building and the US flag was lowered.
China’s foreign ministry said Chinese staff entered the building after the deadline and “took over” the premises.
A US state department spokesperson said: “The consulate has stood at the centre of our relations with the people in Western China, including Tibet, for 35 years.”
“We are disappointed by the Chinese Communist Party’s decision and will strive to continue our outreach to the people in this important region through our other posts in China.”
As the US consulate closed, crowds of local residents gathered outside, with many waving Chinese flags and took selfies.
— People’s Daily, China (@PDChina) July 27, 2020
The US consulate in Chengdu was established in 1985 and had more than 200 staff. It is strategically important because of its proximity to the autonomous region of Tibet.
Diplomatic tensions among the two superpowers has grown since President Trump took office. What started as a simple trade war has escalated after even further following the coronavirus pandemic and Hong Kong security legislature. President Trump has also imposed sanctions on Chinese officials over policies in Tibet and treatment of Muslim minorities Xinjiang.