Fallout continues after President Donald Trump's unveiling of severe tariffs against virtually all U.S. trading partners.

Markets slumped in the United States on Thursday and business are already bracing for impact. Overseas, foreign allies and enemies are weighing their options and threatening retaliation.

The White House, though, said Trump is standing firm on the policy, telling world leaders this is not a negotiation and urging Wall Street to trust the president's plan.