President Donald Trump’s 25% tariffs on steel and aluminum imports came into force Wednesday, triggering concern across export-reliant Asia and immediate reprisals from the European Union and Canada as the global trade war enters a rocky phase.

Donald Trump threatened on Wednesday to escalate a global trade war with further tariffs on European Union goods, as major U.S. trading partners said they would retaliate for trade barriers already erected by the U.

The European Commission launched “ swift and proportionate countermeasures” on US imports, reimposing balancing measures from 2018 and 2020 and adding a new list of industrial and agricultural goods. The EU’s planned countermeasures will apply to American exports worth up to €26 billion, matching the economic scope of the US tariffs.

President Donald Trump imposed sweeping 25% tariffs on all steel and aluminum imported into the United States Wednesday, a policy aimed at leveling the playing field for US manufacturing but a move that threatens to drive up prices on a broad range of consumer and industrial goods for Americans.