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 said Wednesday in Beijing. China planned to “react with firm countermeasures” if the Trump administration didn’t “revoke this erroneous decision,” Wang said.

The State Department said it ordered the consulate shut “to protect American intellectual property and Americans’ private information,” without giving more details. At least two Chinese citizens have been convicted of stealing energy industry trade secrets in Houston in recent years. The consulate is one of five China maintains in the U.S. along with its embassy in Washington.

Asked for specifics on why the consulate was being closed, 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.”

“We are setting out clear expectations for how the Chinese Communist Party is going to behave and when they don’t we’re going to take actions that protect the American people,” he said at a briefing on Wednesday in Denmark where he was meeting the country’s foreign minister.

Futures on the S&P 500 Index dropped after China’s announcement and Treasuries edged higher, but stocks rebounded after the U.S. open, with the S&P climbing to a five-month high on positive earnings news and reports of progress in combating the Covid-19 pandemic.

“So much has happened so quickly that it’s hard not to feel like this is a cycle of major escalation,” said Mira Rapp-Hooper, a senior fellow for Asia studies at the Council on Foreign Relations. “To close a consulate on 72-hours notice should be the result only of ma