Watch: Laura Cooper and David Hale testify in pivotal fourth day of Trump public impeachment hearings

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The fourth round of public impeachment hearings continues with Defense Department official Laura Cooper and State Department official David Hale, who are scheduled to testify before the House Intelligence Committee on Wednesday afternoon.

Cooper, the top Pentagon official for Russia, Ukraine and Eurasia, in closed-door testimony in October described to the committee how she and other national security officials were frustrated by President Donald Trump's decision to withhold $400 million in congressionally approved military aid for Ukraine. And they questioned the legality of the move.

"My sense is that all of the senior leaders of the U.S. national security departments and agencies were all unified in their — in their view that this assistance was essential," Cooper said in a transcript of her testimony, which was released on Nov. 11. "And they were trying to find ways to engage the President on this."

Hale described in his closed-door testimony an effort by Secretary of State Mike Pompeo, to determine who was behind a media campaign to tarnish the then-U.S. ambassador to Ukraine Marie Yovanovitch. She was ousted from her role earlier this year.

U.S. Ambassador to the European Union Gordon Sondland, who testified earlier on Wednesday, told the House Intelligence Committee that Trump directed his personal lawyer Rudy Giuliani, to pursue a "quid pro quo" from Ukraine's newly elected president, Volodymyr Zelenskiy, that involved granting a White House meeting in exchange for investigations into Trump's political rivals. That potential abuse of power is at the heart of the case the Democrats are building against Trump in the impeachment inquiry. Trump has denied any wrongdoing.

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