The directive from DoD General Counsel Paul Ney Jr., a Trump appointee, came the same day that Kurt Volker, a former top U.S. diplomat to Ukraine, testified to a select group of lawmakers behind closed doors on Capitol Hill and provided a tranche of damning text messages that further detailed the administration’s desire to have Ukraine investigate one of Trump’s political opponents.

“In light of heightened interest in the Ukraine Security assistance Initiative (USAI), I write to request your assistance and cooperation in identifying, preserving, and collecting documents and other records regarding the USAFI and in responding to anticipated requests for such materials,” Ney Jr. told DoD departments in a memo that was released Friday.

At the heart of the Ukraine scandal is whether Trump was attempting a quid pro quo by withholding $400 million in foreign military aid in exchange to try and get Ukrainian President Volodymyr Zelensky to agree to investigate former Vice President Joe Biden and his son’s ties to a Ukrainian gas company. On Friday, Ukraine’s top prosecutor announced they would do just that, in addition to reviewing several other criminal cases handled by his predecessors in recent years.

Text messages released Thursday night by the three House committees now spearheading the chamber’s impeachment inquiry—Intelligence, Foreign Affairs and Oversight—following Volker’s daylong testimony showed that U.S. diplomats in the summer were trying to arrange a meeting between Trump and newly-elected Zelensky on the basis that Ukraine announce they’ll investigate the Bidens. The messages also revealed the depth of involvement for Rudy Giuliani, Trump’s personal attorney.

Volker texted U.S. Ambassador to the European Union Gordon Sondland July 19, six days before Trump’s July 25 phone call with Zelensky, where Trump pressured his foreign counterpart to investigate his Democratic rival and his son: “Good. Had breakfast with Rudy this morning — teeing up call with [Zelensky adviser Andrey Yermak] Monday. Must have helped. Most impt is for Zelensky to say that he will help investigation — and address any specific personnel issues — if there are any.”

On July 21, four days before Trump’s call, senior U.S. diplomat to Ukraine Bill Taylor texted Sondland: “Gordon, one thing Kurt and I talked about yesterday was Sasha Danyliuk’s point that President Zelensky is sensitive about Ukraine being taken seriously, not merely as an instrument in Washington domestic, reelection politics.”

Less than an hour before Trump’s July 25 phone call with Zelensky, Volker texted Yermak: “Heard from White House–assuming President Z convinces trump he will investigate/ ‘get to the bottom of what happened’ in 2016, we will nail down date for visit to Washington. Good luck! See you tomorrow – kurt.”

At the time, the U.S. was withholding hundreds of millions of dollars in military aid appropriated by Congress intended to help Ukraine deter Russia in Eastern Europe. Trump last month claimed, “there was never any quid pro quo.”

But U.S. diplomats were concerned about just that, based on the text messages released by the committees. In August, it was revealed military assistance was being held up, prompting additional concerns from Taylor.

“Are we now saying that security assistance and WH meeting are conditioned on investigations?” Taylor texted Sondland on September 1.

Sondland told Taylor to call him. A week later on September 9, Taylor texted Sondland: “As I said on the phone, I think it’s crazy to withhold security assistance for help with a political campaign.”

Sondland responded: “Bill, I believe you are incorrect about President Trump’s intentions. The President has been crystal clear no quid pro quo’s of any kind. The President is trying to evaluate whether Ukraine is truly going to adopt the transparency and reforms that President Zelensky promised during his campaign[.] I suggest we stop the back and forth by text[.] If you still have concerns[,] I recommend you give [Secretary of State Mike Pompeo’s office] a call to discuss them directly.”