The first impeachment inquiry of Donald Trump expanded deeper into his administration on October 7, 2019, when House investigators subpoenaed the Pentagon and the White House Office of Management and Budget for documents concerning the decision to withhold hundreds of millions of dollars in military assistance from Ukraine.
The subpoenas were directed to Defense Secretary Mark Esper and acting OMB Director Russell Vought.
At the center of the investigation was an increasingly important question:
Why had the Trump administration frozen military assistance that Congress had already approved for Ukraine while President Trump and people around him were simultaneously pressing the Ukrainian government for investigations with potential political consequences in the United States?
Investigators wanted the documents that could help answer it.
Congress Goes Looking for the Paper Trail
House Intelligence Committee Chairman Adam Schiff, Oversight Committee Chairman Elijah Cummings and Foreign Affairs Committee Chairman Eliot Engel issued the subpoenas as part of the rapidly expanding impeachment investigation.
Esper and Vought were ordered to produce the requested material by October 15.
The investigators weren't simply asking for general information about Ukraine policy.
They wanted records concerning the suspension, withholding and eventual release of American security assistance to Ukraine.
That included communications inside the administration concerning the decision to freeze the money and the reasons officials had been given for doing so.
The Pentagon subpoena sought 14 categories of documents.
The OMB subpoena sought nine.
Congress was following the money.
Hundreds of Millions in Aid to Ukraine
The assistance mattered because Ukraine had been fighting Russian-backed forces since Russia's seizure of Crimea in 2014 and the beginning of war in eastern Ukraine.
Congress had appropriated hundreds of millions of dollars in security assistance to help Ukraine defend itself.
But during the summer of 2019, the Trump administration placed a hold on portions of that assistance.
The decision reportedly caused concern inside the Departments of Defense and State.
According to information cited by congressional investigators, Pentagon officials argued that the assistance was effective and should be released.
The White House nevertheless maintained the hold for weeks.
That timeline became particularly important because of what else was happening during the same period.
Trump's July 25 Call
On July 25, Trump spoke by telephone with Ukrainian President Volodymyr Zelensky.
According to the memorandum of the call later released by the White House, Trump asked Zelensky for a “favor” and raised investigations involving the 2016 election.
Trump also encouraged Zelensky to investigate matters involving former Vice President Joe Biden and his son Hunter.
Joe Biden was seeking the Democratic presidential nomination and could potentially face Trump in the 2020 election.
Trump maintained that his actions were appropriate and repeatedly insisted there had been no improper quid pro quo.
The impeachment investigation was examining whether the withholding of American assistance was connected to Trump's requests involving investigations.
That made records from the Pentagon and OMB potentially critical evidence.
Why Was the Money Frozen?
Congressional investigators specifically wanted to reconstruct how the decision traveled through the government.
According to reports cited in the October 7 subpoena letters, Trump had directed acting White House chief of staff Mick Mulvaney, who was also OMB director, to freeze the assistance.
The order was then communicated through the budget office to the Pentagon and State Department.
Officials were reportedly told that the administration was reviewing whether the spending was necessary.
But investigators wanted more than the public explanation.
They wanted emails.
They wanted memoranda.
They wanted communications between officials.
They wanted records showing when the freeze was ordered, who ordered it, who objected to it and why it remained in place.
In other words, Congress wanted the government's internal record of what actually happened.
The Inquiry Was Expanding Rapidly
The October 7 subpoenas demonstrated how quickly the impeachment investigation had grown.
What had begun with a whistleblower complaint concerning Trump's dealings with Ukraine was spreading through multiple departments of the federal government.
Investigators were examining the White House.
They were examining the State Department.
They were examining the Pentagon.
Now they were digging into the Office of Management and Budget — the agency positioned to provide crucial documentation about how the Ukraine aid freeze had actually been implemented.
The investigation was no longer centered solely on what Trump had said during one telephone conversation.
It was becoming an examination of how presidential decisions had moved through the machinery of the federal government.
The Administration Resists
The confrontation between Congress and the White House would intensify almost immediately.
The following day, October 8, White House Counsel Pat Cipollone sent congressional leaders a letter declaring that the administration would not cooperate with the impeachment inquiry as it was being conducted.
That resistance would itself become part of the impeachment fight.
The Pentagon and OMB ultimately did not provide the subpoenaed documents to investigators.
The House Intelligence Committee's later impeachment report stated that the White House, State Department, Defense Department, OMB and Energy Department produced no documents in response to the committees' subpoenas.
The dispute therefore became about more than Ukraine.
It became a constitutional confrontation between Congress exercising its impeachment authority and a president directing executive-branch agencies not to participate in the investigation.
The Ukraine Aid Becomes Central to Impeachment
The question surrounding the withheld assistance would eventually become one of the central elements of Trump's first impeachment.
The House investigation concluded that Trump had used the powers of his office to seek political benefit from Ukraine.
Trump and his defenders disputed that conclusion and argued that there was no improper exchange involving the assistance.
On December 18, 2019, the House of Representatives impeached Trump on two articles: abuse of power and obstruction of Congress.
The Senate later acquitted him on both charges.
But months before those historic votes, investigators were still assembling the evidence.
On October 7, they took an important step.
They went to the two places most likely to possess the government's internal records concerning the Ukraine aid freeze:
The Pentagon and the White House budget office.
And they issued subpoenas.