In his opening statement Wednesday during a House impeachment inquiry hearing, U.S. Ambassador to the European Union Gordon Sondland testified that there was a quid pro quo for Ukraine to announce investigations into Burisma and 2016 election interference that came from Rudy Giuliani at the guidance of President Trump.

"Was there a 'quid pro quo?'" Sondland asked. "The answer is yes."

Sondland said that Giuliani, Trump's personal attorney, communicated to the Ukrainians that a White House meeting between President Trump and Ukraine President Volodymyr Zelensky was conditioned on a public statement announcing the launch of investigations, and that Giuliani was acting at President Trump's behest.

"Mr. Giuliani expressed those requests directly to the Ukrainians," Sondland said. "Mr. Giuliani also expressed those requests directly to us. We all understood that these prerequisites for the White House call and White House meeting reflected President Trump's desires and requirements."

Later in the hearing, GOP counsel Stephen Castor pressed Sondland on his claim that the prerequisites for the meeting originated with President Trump.

"Did the President ever tell you personally about any pre-conditions for anything?" asked Castor, to which Sondland responded, "no."

Castor then questioned Sondland on his assertion that Giuliani was expressing Trump's desires and requirements — "How do you know that?" Castor said. In response, Sondland admitted that he "assumed" that by referring him to Giuliani, Trump was directing the pre-conditions.

Sondland also claimed that the quid pro quo for a White House meeting was "no secret," but was open knowledge among Trump's inner circle.

He cited a July 19 email copied to acting White House chief of staff Mick Mulvaney, Energy Secretary Rick Perry, Secretary of State Mike Pompeo and several other senior officials in saying that "everybody was in the loop."

Sondland's testimony marks the first time since the public hearings began that several of Trump's senior officials have been named as being directly involved in the events surrounding the impeachment probe.

What about the military aid?

Regarding the allegation that $400 million in military aid was withheld as part of the quid pro quo for pressuring the launch of investigations into Trump's political opponents, Sondland provided a less air-tight confirmation.

Sondland testified that "in the absence of any credible explanation" for the aid not being released, he "later came to believe" that the military aid would not be delivered to Ukraine without a public announcement of investigations into Burisma and 2016 election meddling.

Sondland said that he told Vice President Mike Pence before his Sept. 1 meeting with Zelensky that he "had concerns that the delay in aid had become tied to the issue of investigations."

It should be noted that Vice President Pence's office has officially denied that this conversation ever took place.

On the specific issue of military aid, Sondland's testimony could provide Republicans the space to argue that military aid being tied to investigations is an allegation still based on hearsay and assumptions rather than any substantive evidence.

Why won't the State Department let Sondland see relevant documents?

In his opening statement, Sondland lamented the fact that during the impeachment inquiry process he has not been permitted access to all of his "phone records, State Department emails, and other State Department documents."

"I was told that I could not work with my EU staff to pull together the relevant files," he stated, before acknowledging that having all of the relevant materials would have been "very helpful" in recalling the details for his testimony.

Despite repeated requests to the State Department, Sondland said the materials have still not been provided to him, and that, in fact, the State Department has also "refused to share these materials with the [House Intelligence Committee]."