Acting US Ambassador to Ukraine William Taylor told the House panels heading the impeachment probe that he first heard of US military aid for Ukraine being tied to a public announcement about an investigation into Joe Biden during a conversation with President Trump’s top adviser for Russia and Europe.

Taylor said he had a phone call with Tom Morrison who described a conversation US Ambassador Gordon Sondland had with Andriy Yermak, a top aid to Ukrainian President Volodymyr Zelensky in Warsaw, Poland, in September.

“What I know for sure is what Mr. Morrison told me that he must have heard Ambassador Sondland tell Mr. Yermak. And as I said, this was the first time I’d heard those two put together, those connected,” Taylor told the panel during his Oct. 22 deposition, according to the transcript released Wednesday.

Taylor was asked if the release of the nearly $400 million in military aid was a condition of Zelensky launching an investigation into the former vice president.

“That was my clear understanding, security assistance money would not come until the President committed to pursue the investigation,” Taylor replied.

“Are you aware that quid pro quo literally means this for that?” he was asked.

“I do,” Taylor said.

Earlier in his deposition, Taylor said Sondland, Energy Secretary Rick Perry, Ambassador Kurt Volker and Trump lawyer Rudy Giuliani were running an “irregular, informal channel of US policymaking with respect to Ukraine.”

“I was clearly in the regular channel, but I was also in the irregular one to the extent that Ambassadors Volker and Sondland included me in certain conversations. Although this irregular channel was well connected in Washington, it operated mostly outside of official State Department channels,” Taylor said.