China announced sanctions on Sunday against five US defense firms in response to their involvement in arms sales to self-ruled Taiwan, which Beijing claims as part of its territory.
China has vowed to one day seize Taiwan, while the US Congress requires the supply of weapons to the self-governing democracy for its defense.
Last month, the US State Department approved a $300-million arms package to strengthen Taipei's joint battle command and control system, prompting Beijing to say it would take unspecified "countermeasures" against the companies involved.
China's foreign ministry on Sunday named those companies as BAE Systems Land and Armament, Alliant Techsystems Operation, AeroVironment, ViaSat, and Data Link Solutions.
"The countermeasures consist of freezing the properties of those companies in China, including their movable and immovable property, and prohibiting organizations and individuals in China from transactions and cooperation with them," the ministry said.
"The US arms sales to China's Taiwan region… seriously harm China's sovereignty and security interests," it added.
Beijing has ratcheted up pressure on Taiwan since independence-leaning President Tsai Ing-wen took power there in 2016.
It regularly sends warplanes and vessels near the island, where the defense ministry recently also reported several sightings of balloons from the mainland.
Both Washington and Taipei have warned Beijing against seeking to influence the presidential elections being held in Taiwan this month.
