U.S. Federal Reserve Chair Jerome Powell said the U.S. central bank had received grand jury subpoenas from the Justice Department that could lead to a criminal indictment, marking a sharp escalation in former President Donald Trump’s attacks on the Fed.

In a written and video statement released Sunday evening, Powell said the subpoenas were connected to his June congressional testimony regarding ongoing renovations at the Fed’s headquarters. He added that the action “should be seen in the broader context of the administration’s threats and ongoing pressure.”

“The threat of criminal charges is a consequence of the Federal Reserve setting interest rates based on our best assessment of what will serve the public, rather than following the preferences of the president,” Powell said.