READ: Laura Cooper's Testimony In Impeachment Inquiry House investigators spoke with Laura Cooper, deputy assistant secretary of defense, in October. Cooper is responsible for policy toward Russia and Eastern Europe.
NPR logo READ: Defense Department Official's Impeachment Inquiry Testimony

READ: Defense Department Official's Impeachment Inquiry Testimony

Laura Cooper, the deputy assistant secretary of defense for Russia, Ukraine and Eurasia, arrives at the U.S. Capitol on Oct. 30. A transcript of her testimony to House investigators in the impeachment inquiry was released on Monday. Mandel Ngan/AFP via Getty Images hide caption

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Mandel Ngan/AFP via Getty Images

Laura Cooper, the deputy assistant secretary of defense for Russia, Ukraine and Eurasia, arrives at the U.S. Capitol on Oct. 30. A transcript of her testimony to House investigators in the impeachment inquiry was released on Monday.

Mandel Ngan/AFP via Getty Images

Updated at 7:10 p.m. ET

The top Pentagon official who oversaw Russia and Eastern Europe told House impeachment investigators that Ukrainian officials had raised the issue of the suspension of security aid as early as August.

"I knew from my Kurt Volker conversation and also from sort of the alarm bells that were coming from Ambassador [Bill] Taylor and his team that there were Ukrainians who knew about this" Laura Cooper, the deputy assistant secretary of defense, said Oct. 23. Transcript of her closed-door deposition was released Monday.

She said Volker, who at the time served as U.S. special envoy for Ukraine, told her during this conversation, which occurred on or about Aug. 20, that he was talking to an aide to Ukrainian President Volodymyr Zelenskiy about making a statement, "disavowing election interference." She said Volker told her about "the path that he was pursuing to lift the hold" on security aid was to "get them to make this statement."

That assertion is at the heart of the impeachment inquiry into President Trump. Democrats are looking to build a case that the president sought a quid pro quo with Zelenskiy: an investigation into the Bidens in exchange for a White House visit and the release of aid. The Trump administration, which has released the transcript of the call, denies such an offer was made, calling the conversation between the two leaders "perfect."

Read Cooper's testimony here.