The New York Democrat asks Fine to inform his office and the public of the date "when personnel at your agency or department were last notified of their legal rights to make protected disclosures anonymously" along with a request for written certification "from your agency or department's general counsel that he or she has not and will not permit retaliation or reprisals against anyone who has, or in the future makes, protected disclosures of presidential misconduct."
Amid uncertain futures, other witnesses in the impeachment investigation have already left the administration or distanced themselves from the White House by moving into roles at different agencies as Trump.
Still, Vindman is expected to return to the Pentagon, though it's still unclear what his assignment will be until he's expected to attend war college this summer.
"We welcome back all of our service members, wherever they serve, to any assignment they are given," Defense Secretary Mark Esper had said Friday when asked about Vindman's expected ouster.
Drawing on Trump's Ukraine conduct, Schumer said in concluding his letter to Fine that "without the courage of whistleblowers and the role of Inspectors General, the American people may never have known how the President abused his power in the Ukraine scandal."
"It is incumbent on you that whistleblowers like LTC Vindman -- and others who put their lives on the line to protect our freedoms -- are protected for doing what we hope and expect those who serve our country will do when called: tell the truth."