China says it has launched an anti-dumping probe into imports of a widely used plastic from the U.S., EU, Taiwan and Japan. 

BBC News says the announcement from the People's Republic of China’s Ministry of Commerce that it will investigate imports of polyoxymethylene copolymer — which is used in electronics and cars — is a signal that China will hit back in its trade disputes with the U.S. and Europe.

President Biden announced punitive new tariffs on Chinese imports on May 14, raising rates for a vast array of imports, from electric vehicles to steel and aluminum.

Read More: U.S. Manufacturers Praise New Tariffs on Medical Supply Imports from China

Ahead of that announcement, a spokesperson for China's foreign ministry said it would "take all necessary measures to safeguard its legitimate rights and interests."

Separately on May 20, China sanctioned three American defense firms over their sales of weapons to Taiwan, state media said.

General Atomics Aeronautical Systems, General Dynamics Land Systems, and Boeing Defense, Space & Security are barred from "import and export" business in China.

Meanwhile, Europe has launched a series of probes into Chinese imports.

On May 17, the EU said it would launch an investigation into Chinese tinplate steel, and in April said it was probing two Chinese solar panel makers that it says benefit from government subsidies.

The European Commission, which oversees the EU's trade policies, has also given itself a July 4 deadline to decide whether to impose measures against imports of Chinese-made EVs.