President Donald Trump has fired Federal Reserve Governor Lisa Cook, a sharp escalation in his battle to exert greater control over what has long been considered an institution independent from day-to-day politics.

I have determined that there is sufficient cause to remove you from your position,” Mr. Trump said in a letter. Her dismissal threatened to touch off a landmark legal battle over the Fed’s independence.

The president said he was removing Cook from the Board of Governors immediately for "cause" but it was unclear if he has the authority to do so.