A key leader in the world economy is warning that undue interference in the Federal Reserve’s operations by President Donald Trump could pose a serious economic risk to the U.S. and the rest of the world. European Central Bank President Christine Lagarde said in an interview with Radio Classique on Monday that efforts to remove Fed Chair Jerome Powell or Fed Governor Lisa Cook would “represent a very serious danger for the U.S. economy and the world economy.” “If U.S. monetary policy were no longer independent and instead dependent on the dictates of this or that person, then I believe...