President Trump has ordered that the staff of the National Security Council be significantly reduced as he seeks to fend off an impeachment inquiry sparked partly by a whistleblower complaint involving the NSC, Bloomberg reports. Five sources cited in the Bloomberg report confirmed the move, saying Trump’s request had been handed down to top agency officials by acting White House Chief of Staff Mick Mulvaney and National Security Adviser Robert O’Brien. Two of the sources said the staff reduction stemmed from a desire to boost efficiency as O’Brien transitions into his new role as national security adviser.

The National Security Council, which currently employs just over 300 people, was mentioned in the whistleblower complaint over Trump’s dealings with Ukraine that triggered an impeachment inquiry.