WASHINGTON — President Donald Trump is taking a blowtorch to the rules that have governed world trade for decades. The “reciprocal’’ tariffs that he announced Thursday are likely to create chaos for global businesses and conflict with America’s allies and adversaries alike.

I’ve decided for purposes of fairness that I will charge a reciprocal tariff,” Trump said in the Oval Office at the proclamation signing. “It’s fair to all. No other country can complain.”