After three witnesses last week painted a broad picture of a U.S. foreign policy hijacked by political interests, this week the impeachment inquiry into President Trump began with testimony Tuesday from four people who serve inside the White House and on the front lines of U.S. foreign policy in Ukraine.

Tuesday’s hearings featured:

All four previously testified in closed-door depositions. Here’s what we learned from their latest testimony.

1. A big correction from Volker

Volker — like the ambassador to the European Union, Gordon Sondland — was forced to correct his testimony after other witnesses called it into question.

The most important clarification came with regard to a July 10 meeting in which Sondland has now acknowledged he brought up investigations with Ukrainian leaders — after previously not disclosing that. Volker had previously testified that there was no mention during that meeting of the investigations Trump and his personal attorney Rudolph W. Giuliani were seeking. But other witnesses indicated then-national security adviser John Bolton shut down the meeting because Sondland broached them.

So on Tuesday, Volker confirmed it, saying Sondland made “a general comment about investigations” toward the end of the meeting — but Volker said that he himself might not have been around for some of the fallout.

He added, “I think all of us thought it was inappropriate.”

2. Volker says anti-Biden campaign was also inappropriate

Another key shift in his testimony came with respect to whether this effort was a political one. Volker has testified that he didn’t push for an investigation of former vice president Joe Biden and his son Hunter; he now says that he should have connected the dots between the Bidens and Burisma Holdings, the Ukrainian company that employed Hunter Biden.

He also said the entire effort was wrong.

“In retrospect, I should have seen that connection [between Burisma and Biden] differently, and had I done so, I would have raised my own objections,” he said.

Volker also added that there was no basis for Trump and Giuliani’s idea that Joe Biden’s actions in Ukraine — they allege he was trying to shut down an investigation of Burisma to benefit his son, despite plenty of contrary evidence — were improper.

“The accusation that Vice President Biden was acting inappropriately didn’t seem at all credible to me,” he said. He added, “The allegations against Biden are self-serving and not credible.”

Volker, it bears mentioning, is one of three Republican-requested witnesses who are testifying, along with Morrison.

3. An unknown Vindman contact in the intel community

In one of the tensest exchanges in the first hearing session, Vindman disclosed that he spoke with an intelligence-community official about Trump’s July 25 phone call with Ukrainian President Volodymyr Zelensky, but he declined to identify the official, saying his attorney had advised him not to do so.

When Rep. Devin Nunes (R-Calif.), the ranking Republican on the House Intelligence Committee, began asking for more details about the person, Chairman Adam B. Schiff (D-Calif.) interjected and warned about any attempts to out the anonymous whistleblower who first filed a complaint related to the call.

Nunes had made clear in his opening statement how important he felt it was to hear directly from the whistleblower, who has declined to give up anonymity and is legally entitled to it.

Nunes sought to argue that if Vindman didn’t know who the whistleblower was, he wouldn’t actually be outing anyone. But Vindman stood his ground.

“Per the advice of my counsel, I’ve been advised not to answer specific questions about members of the intelligence community,” he said.

Nunes soon suggested that Vindman might want to instead plead the Fifth Amendment — the one protecting witnesses against self-incrimination — to which Vindman’s attorney objected. “This does not call for an answer that is invoking the Fifth or any theoretical issue like that,” he said. “We’re following the ruling of the chair.”

Whoever the whistleblower is, the vast majority of that person’s claims were secondhand and have been confirmed by other witnesses, rendering the whistleblower’s unique insights into the impeachment inquiry somewhat limited.

4. GOP’s thinly veiled attacks on Vindman, and two striking rebuttals

Vindman, who was born in Ukraine when it was part of the Soviet Union and immigrated to the United States as a young child, has been attacked in conservative media arguably more than any other witness — including with suggestions that his loyalty may not be to the United States. Schiff took time at the beginning of the hearing to warn Republicans against impugning Vindman’s character, invoking Fox News.

Against that backdrop, Vindman closed his opening statement with this note to his Soviet-born father, who brought his family to the United States.

“Dad, my sitting here today, in the U.S. Capitol, talking to our elected officials, is proof that you made the right decision 40 years ago to leave the Soviet Union and come here to the United States of America in search of a better life for our family,” he said. “Do not worry. I will be fine for telling the truth.”

Later in the hearing, Vindman also took exception to Nunes calling him “Mr. Vindman.”

“Ranking member, it’s Lieutenant Colonel Vindman,” he said.

GOP counsel Stephen Castor asked Vindman about Oleksandr Danylyuk, a top Ukrainian official, having suggested that Vindman could be Ukraine’s defense minister — a very high-ranking position in the country’s government. (Danylyuk told The Washington Post, “Clearly this was just a joke,” and added, “We had much more serious issues to discuss with different people.”)

Vindman testified that he wasn’t sure whether the offer was a real one, given that he’s not a high-ranking official in the U.S. military, and that he reported it to his superiors.

“I’m an American,” he said. “I came here when I was a toddler. I immediately dismissed these offers, did not entertain them. … The whole notion is rather comical.”

Castor never raised the issue of Vindman’s loyalties, but he did suggest that the offer might present a conflict of interest. Vindman countered that his superiors never made such a determination.

Later, Rep. Chris Stewart (R-Utah) noted that Vindman was wearing his uniform despite usually wearing a suit to work. Stewart actually praised him for it, but it seemed a convenient way to inject a popular attack against Vindman. And just moments later, Stewart made clear he wasn’t being terribly friendly to Vindman. “Do you always insist on civilians calling you by your rank?” he asked.

Castor also asked Morrison about allegations that Vindman had leaked information to the press, even after Vindman categorically denied it under oath.

5. Vindman and Morrison align — and diverge — on a key event

One key area of agreement between both parties’ witnesses — Morrison and Vindman — was on the moving of the rough transcript of the July 25 call to a highly secretive, code-word-level server. They both testified that it wasn’t a big deal.

Vindman said he didn’t see it as “anything nefarious,” adding, “I just understood that they wanted to keep it into a smaller group.”

Morrison agreed in his testimony that he didn’t see any “malicious intent” in storing the call on the server.

But they diverged in one key respect. Morrison said that “it was represented to me that it was a mistake” — echoing his previous testimony. But Vindman described it as having been deliberate and intended to shield a sensitive call.

6. Trump’s lack of interest in ‘corruption’

Vindman confirmed reporting that he had drafted talking points for Trump ahead of the president’s April phone call with Zelensky and that those talking points included Ukrainian corruption.

“Those were the recommended talking points that were cleared through the NSC staff for the president,” Vindman said.

That’s significant because Trump didn’t bring up corruption on the call, according to a transcript of it that the White House released last week — even as the White House’s readout of the call incorrectly stated that it had been discussed.

The Post previously reported that the readout was drafted before the call took place and wasn’t corrected afterward. But that makes two indications that corruption was supposed to be brought up on the call and that Trump didn’t do it.

That undermines the White House defense that Trump was truly concerned about corruption in Ukraine and that’s why he was pressing for specific investigations. That argument is already undermined by multiple pieces of evidence — including Giuliani’s public comments and the fact that Trump has shown interest in only two investigations, both of which would carry obvious personal benefits for him. Vindman’s testimony indicates that Ukrainian corruption wasn’t much of a priority for Trump, at least as of April.

David Holmes, a U.S. official who was in Ukraine, also testified last week that Sondland told him that Trump didn’t “give a s---” about Ukraine and just wanted his specific investigations.

In later testimony, though, Volker indicated Trump was deriding Ukraine as a corrupt place at a May 23 briefing — after Giuliani’s effort became public.

“He had just a string of comments that ‘Ukraine is a terrible place, they’re all corrupt, they’re terrible people, they tried to take me down,’ ” Volker said. “He said that Zelensky is no different” from other Ukrainian politicians.

Volker indicated that Giuliani had convinced Trump of this and that other aides couldn’t disavow him of that belief.

7. Vindman: Nothing ‘nefarious’ in rough transcript omitting Burisma

Schiff and his counsel, Daniel Goldman, pressed Vindman on reports that he had recommended that the rough transcript of Trump’s call with Zelensky be corrected to include the word “Burisma.”

The idea appeared to be that something may have been omitted from the official transcript, which included a number of curious ellipses, that reflected poorly on Trump.

Vindman and Williams, both of whom were on the call, testified that Burisma was, in fact, mentioned. But Vindman suggested that its omission from the rough transcript wasn’t a big deal. He indicated that the drafting of the rough transcript followed a normal process and that he didn’t see anything wrong in his two suggestions not being included.

“When I first saw the transcript without the two substantive items I attempted to include, I didn’t see that as nefarious,” he said.

Paul Sonne contributed to this report.