Longtime Defense Department official Laura Cooper will testify publicly Wednesday about events she witnessed as part of her role coordinating U.S. assistance to Ukraine’s military. Lawmakers will probably focus on what she knew — and didn’t know — about the holdup of military aid to Ukraine, and whether that decision was an attempt to pressure the country’s president into opening investigations that stood to benefit President Trump politically.

Who she is

Cooper is the deputy assistant secretary of defense for Russia, Ukraine and Eurasia. Last month, she told House investigators that her role primarily focuses on the Department of Defense’s long-term strategy and current policy toward Russia.

Much of her work in Ukraine focused on fostering a strong relationship with the country’s Defense Ministry and “building the capacity of the Ukrainian Armed Forces to resist Russian aggression,” she testified in October.

Why her testimony matters

Part of Cooper’s portfolio included working to support Ukraine’s defense apparatus, and she learned over the course of several days in the summer that U.S. military aid to the country had been put on hold for reasons that she and other officials found legally questionable.

Cooper’s knowledge of discussions among various federal agencies about withholding this aid may help answer the all-important question of who, exactly, directed that the aid be held, and whether it was done with explicit conditions on its release.

What we learned from her testimony

It was Cooper’s October closed-door deposition that was held up for several hours after a group of Republicans stormed the secure area where the closed-door impeachment hearings were being held, to protest the secrecy of the proceedings.

When she eventually got to testify, Cooper shared that she had learned over the course of several days in July that Trump had “concerns about Ukraine and Ukraine security assistance.” She said that on July 26, a budget official clarified that the aid had been put on hold for reasons “relate[d] to the President’s concerns about corruption.”

Cooper testified that she had a “very strong inference” that the Ukrainians knew the funding was on hold after speaking with then-U.S. special envoy to Ukraine Kurt Volker. Volker played a key role in facilitating a meeting between Trump and Ukrainian President Volodymyr Zelensky, and text messages the former special envoy previously released implied that such a meeting was predicated on Zelensky’s agreeing to publicly announce a corruption investigation.

That undercut a key defense put forward by Trump and his defenders: that there could be no quid pro quo because Ukraine did not know that aid was being withheld.

A key exchange from her closed-door testimony

The crux of Cooper’s testimony is her description of a meeting she participated in July 26. She testified it became clear to her that foreign aid had been held up because of Trump’s concerns about corruption and that other officials became concerned about the legality of the decision.

Cooper: [...]And there it was, to me anyway in my experience, it was the fist time it was stated very clearly what — that yes, it is [Foreign Military Financing and Ukraine Security Assistance Initiative funds] are both affected by this hold and that it relates to the President’s concerns about corruption. And that is what in that meeting Mike Duffey from OMB said.
Q: And the President is authorized to have these types of holds placed. Correct?
Cooper: Well, I’m not an expert on the law, but in that meeting immediately deputies began to raise concerns about how this could be done in a legal fashion because then was broad understanding in the meeting that the funding -- the State Department funding related to an earmark for Ukraine and that the DOD funding was specific to Ukraine security assistance.
Cooper: So the comments in the room at the deputies’ level reflected a sense that there was not an understanding of how this could legally play out. And at that meeting the deputies agreed to look into the legalities and to look at what was possible.

What to expect from her public testimony

Expect lawmakers to pepper her with questions about what she knew about the hold on military aid and what she did or did not witness firsthand. Because she was not a direct participant in many of the events central to the impeachment proceedings, the president’s Republican supporters may attempt to undercut her testimony as hearsay.