US President Donald Trump's 25 percent tariffs on all imports of steel and aluminium came into effect on Wednesday, without any exemptions for the country’s traditional allies. The import duties were welcomed by some American metal producers who want protection against what they believe is unfair competition. The European Union has vowed to retaliate with its own measures targeting 26-bn euros worth of US goods entering the common market. Also, fears of a recession rattle global stock markets.