China’s foreign ministry announced sanctions on Friday targeting 10 individuals and 20 US defence firms, including Boeing’s St. Louis branch, over arms sales to Taiwan.

The measures freeze any assets the companies and individuals hold in China and bar domestic organisations and individuals from doing business with them, the ministry said.

Individuals on the list, including the founder of defence firm Anduril Industries and nine senior executives from the sanctioned firms, are also banned from entering China, it added.

Other companies targeted include Northrop Grumman Systems Corporation and L3Harris Maritime Services.

The move follows Washington’s announcement last week of $11.1 billion in arms sales to Taiwan, the largest ever US weapons package for the island, drawing Beijing’s ire.

“The Taiwan issue is the core of China’s core interests and the first red line that cannot be crossed in China-US relations,” a Chinese foreign ministry spokesperson said in a statement on Friday.

“Any provocative actions that cross the line on the Taiwan issue will be met with a strong response from China,” the statement said, urging the US to cease “dangerous” efforts to arm the island.

China views democratically-governed Taiwan as part of its own territory, a claim Taipei rejects.

The US is bound by law to provide Taiwan with the means to defend itself, though such arms sales are a persistent source of friction with China.