Shares in steel producer ArcelorMittal South Africa opened 2% weaker on the Johannesburg Stock Exchange on Tuesday after U.S. President Donald Trump imposed tariffs on steel and aluminium imports to the United States.

U.S. stocks closed higher as investors snatched up aluminum and steel shares on President Trump's plan for a 25% tariff on those imports.

President Donald Trump is expected to introduce new 25% tariffs on Monday on all steel and aluminium imports into the U.S., on top of existing metals duties, in another major escalation of his shake-up of trade policy.