The Justice Department has opened an investigation into Federal Reserve Chair Jerome Powell’s statements to Congress regarding renovations of the Fed’s headquarters in Washington, according to a statement from Powell.

The move is a sharp escalation of President Donald Trump’s ongoing clash with the Fed chief, who the president has long pushed to lower interest rates.

The DOJ sent subpoenas to the Fed regarding Powell’s statements to Congress on the central bank’s headquarters, Powell said.

“I have deep respect for the rule of law and for accountability in our democracy. No one—certainly not the chair of the Federal Reserve—is above the law. But this unprecedented action should be seen in the broader context of the administration’s threats and ongoing pressure,” Powell said in a statement Sunday night.