In his opening statement before congressional impeachment investigators on Tuesday, Lt Col Alexander S Vindman planned to describe his concerns that Donald Trump’s plot to undermine Joe Biden was undermining US foreign policy in Ukraine.

Here are five key takeaways:

1 White House call summary is accurate

As the top Ukraine expert on the national security council (NSC), Vindman was on the 25 July phone call between Trump and the Ukrainian president, Volodymyr Zelenskiy. He planned to testify that a call summary released by the White House is accurate: “As the transcript is in the public record, we are all aware of what was said.”

2 Vindman took concerns to NSC lawyer

Vindman planned to describe multiple scenes in which White House discussions about Ukraine policy, including discussions with Ukrainians, were interrupted by an insistence that Ukraine announce baseless investigations tied to Biden. “I did not think it was proper to demand that a foreign government investigate a US citizen, and I was worried about the implications for the US government’s support of Ukraine,” Vindman planned to say. Vindman planned to describe how on multiple occasions he took his concerns to the top lawyer for the national security counsel, as at least one other colleague did.

3 Vindman’s testimony appears to conflict with Sondland’s claims

As multiple witnesses have previously, Vindman planned to finger ambassador to the EU Gordon Sondland, as the Trump administration’s point man in extracting the “deliverable” – a Biden investigation announcement – from Ukraine. Vindman planned to say: “I stated to Ambassador Sondland that his statements were inappropriate, that the request to investigate Biden and his son had nothing to do with national security.” That testimony appears to conflict sharply with Sondland’s own claims to ignorance about any effort to negotiate a deal with Ukraine involving a Biden investigation.

4 Vindman’s family fled the former Soviet Union

Vindman, a career public servant and soldier, arrived in the US at age three when his family fled the former Soviet Union. He is a US army officer, a lieutenant colonel, with two decades of experience in the military. He was decorated with a Purple Heart after being wounded in an improvised explosive device attack while deployed in Iraq.

5 White House accused Vindman of ‘espionage’ against Trump

The White House and media allies have launched a character smear against Vindman, accusing him of disloyalty to the US and of “espionage” against Trump. Trump seemed surprised that Vindman was on the phone call and wondered on Twitter why so many people were listening: “I knew people were listening in on the call (why would I say something inappropriate?), which was fine with me, but why so many?” Trump tweeted. “Why are people that I never even heard of testifying about the call.”