USA shuts down Chinese consulate in Houston.

China vowed retaliation after the U.S. forced the closure of its Houston consulate, in one of the biggest threats to diplomatic ties between the countries in decades.

The U.S. government gave China three days to close its consulate in America’s fourth-most populous city in an “unprecedented escalation,” Foreign Ministry spokesman Wang Wenbin told a regular briefing Wednesday in Beijing. China planned to “react with firm countermeasures” if the Trump administration didn’t “revoke this erroneous decision,” Wang said.

The U.S. State Department subsequently confirmed in a statement that it had ordered the consulate shut “to protect American intellectual property and Americans’ private information.” It said international agreements required diplomats to respect the laws and regulations of the host nation and not interfere in its internal affairs.

The first signs of trouble came when Houston police and firefighters descended on the consulate following witness reports that papers were being burned outside in open containers, the Houston Chronicle and two local TV stations reported on Tuesday night, citing local police. In videos posted online by local media outlets, fires could be seen in multiple containers, with smoke rising into the sky.

Futures on the S&P 500 Index dropped after China’s announcement and Treasuries edged higher, though stock futures later pared their losses and the dollar turned lower.

Asked for specifics on why the consulate was being closed, U.S. Secretary of State Michael Pompeo responded with broad remarks about China’s actions on intellectual property, saying it was “costing hundreds of thousands of jobs.”