From the WSJ:
The European Central Bank cut its key interest rate and launched a sweeping package of bond purchases Thursday that commits the bank to ultraloose monetary policy for a long period, jolting European financial markets and triggering an immediate response from President Trump.
The effect, of course, was a weaker Euro–which fell to $1.10. The response from the President:
“European Central Bank, acting quickly, Cuts Rates 10 Basis Points. They are trying, and succeeding, in depreciating the Euro against the VERY strong Dollar.”
Thus far the initial criticism has been focused on the Fed–for having presumably a overly stringent monetary policy that helps support the value of the U.S. dollar. But the tools in the US toolbox to retaliate are considerable, including possible trade penalties or sanctions.
The full story is here.