(CNN) The Trump administration is withholding 20 emails pertaining to frozen Ukraine military aid between a top aide to President Donald Trump's acting chief of staff and an official at the White House Office of Management and Budget, the New York Times reported Friday.

The New York Times had filed a Freedom of Information Act lawsuit in late November for emails exchanged between Robert Blair , an assistant to Trump and senior adviser to acting chief of staff Mick Mulvaney, and Mike Duffey , a Trump political appointee who's the OMB official responsible for overseeing national security money.

The withholding of the emails highlights how extensively the administration has refused to disclose to the public or to Congress information about Ukraine that led to the President's impeachment, and the standoff over public records could result in a judge's intervention.

"All 20 documents are being withheld in full," Dionne Hardy, OMB's Freedom of Information Act officer, wrote of the 40 pages of emails in a letter to the Times

Hardy characterized the decision as allowed under the law to protect "both deliberative and presidential communications, the disclosure of which would inhibit the frank and candid exchange of views that is necessary for effective government decision-making."

In mid-December, OMB agreed to produce public records the Times had requested after the paper sued for the documents. At that time, the agency made no promises that information in the records would be unredacted.

The Times previously said in court filings that it might ask for a judge's intervention if there were redactions or any documents were withheld.

Blair and Duffey have emerged as central figures in Trump's Ukraine dealings and subsequent impeachment, with Senate Minority Leader Chuck Schumer , a New York Democrat, calling for them to appear at the Senate trial.

Both Duffey and Blair refused to testify in the House investigation that led to the President's impeachment, even under subpoena. Agencies including OMB, the Defense Department, the State Department and the White House turned over none of the documents requested by the House. And public records of what they discussed are scant.

While some news organizations like the Times have sued for access to executive branch documents about Trump's hold on the Ukraine aid, others have only heard details from sources about records that exist.

According to a report Thursday by Just Security , a website focusing on reporting and analysis of national security law and policy, Duffey cited in an August 30 email "Clear direction from POTUS to continue to hold" the Ukraine aid -- despite growing legal concerns within the Pentagon and questions prompted by news of the hold becoming public just days before.

Roughly 90 minutes after Trump spoke to Ukrainian President Volodymyr Zelensky on July 25 and pressed him for investigations that could boost Trump politically, Duffey ordered the Pentagon to freeze security funding for the country, according to documents released last week from a separate request by the Center for Public Integrity.

"Based on guidance I have received and in light of the Administration's plan to review assistance to Ukraine, including the Ukraine Security Assistance Initiative, please hold off on any additional DoD obligations of these funds, pending direction from that process," Duffey wrote to select OMB and Pentagon officials on July 25.

Duffey also seemed to suggest that the hold could raise concerns, noting that "given the sensitive nature of the request, I appreciate your keeping that information closely held to those who need to know to execute direction."

The Times previously reported that Blair had written in an email to Mulvaney that while withholding the Ukraine aid would be possible, "expect Congress to become unhinged" if the White House held back the congressionally appropriated funds.

Several executive branch agencies have turned over some documents related to Ukraine and impeachment in recent weeks, after lawsuits from transparency groups seeking access to various records. While the Times' public records request was one of the most limited that ended up in court, other documents released by agencies such as the Defense Department or the State Department have had at least some unredacted information in them.

Many public records requests related to Ukraine and impeachment, including dozens from CNN, have yet to see final responses from agencies.