(CNN) A key Pentagon official told House impeachment investigators that former US special envoy to Ukraine Kurt Volker told her Ukrainian officials were alarmed in August that US security aid was being held up — an indication Kiev was aware of the delay earlier than it was reported publicly, according to a deposition transcript released Monday.

Laura Cooper, the Pentagon's deputy assistant secretary for Russia, Ukraine and Eurasia, told lawmakers behind closed doors last month that she met with Volker in August to discuss the hold on aid. She said Volker told her in their meeting that he was attempting to lift the hold on the aid by having the Ukrainians deliver a public statement that they would launch the investigations being sought by President Donald Trump.

She described Volker seeking a statement from the Ukrainians about opening investigations into election interference that would trigger a release in the aid.

"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," Cooper said, describing the Ukrainians as aware of the freeze on aid in August 2019. "The context for the discussion that I had with Ambassador Volker related specifically to the path that he was pursuing to lift the hold would be to get them to make this statement, but the only reason they would do that is because there was, you know, something valuable."

Cooper's deposition was one of three transcripts released Monday by House Democrats. They also made public the interviews last month of two former deputies of Volker, Catherine Croft and Christopher Anderson

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