(CNN) Lt. Col. Alexander Vindman, the National Security Council's top Ukraine expert, testified this week that he was told not to talk with anyone about the July 25 call between President Donald Trump and the Ukrainian President, according to a source familiar with the testimony.
Vindman testified that he was concerned about the July call between Trump and Ukrainian President Volodymyr Zelensky, and he took those concerns to National Security Council lawyer John Eisenberg, who told him not to discuss the call, the source said.
Eisenberg and NSC lawyers moved the transcript of the call onto a higher security system than what's typically used for presidential calls — a decision that's among the issues Democratic impeachment investigators are probing.
Politico first reported that Eisenberg told Vindman not to discuss the call.
Vindman was one two National Security Council officials to testify before the House Intelligence, Foreign Affairs and Oversight committees this week behind closed doors. Vindman told lawmakers that while he was concerned about the July call, he testified that the rough transcript released by the White House was mostly accurate. But he proposed two edits to the transcript — to add references to Burisma, the company that hired Hunter Biden, and Vice President Joe Biden's tapes — which were ultimately not included.
Vindman also testified that he was convinced Trump was personally blocking the release of US security aid to Ukraine in order to force Ukraine to publicly announce an investigation that could help Trump politically. Vindman also believed there was a connection between Ukraine's investigation and a one-on-one meeting between Trump and Zelesnky following a July meeting before the Trump-Zelensky call. Both Vindmand and former White House aide Fiona Hill reported their concerns about the meeting to Eisenberg, Vindman testified.
The White House declined to weigh in on Vindman's testimony Friday.
"We can't comment on testimony we didn't get to be in the room to hear," White House press secretary Stephanie Grisham said.
Tim Morrison, the National Security Council's top Russia and Europe adviser, testified Thursday that the concerns he had over the July call was the transcript leaking. But he did not think there was anything wrong or illegal with the call itself, according to his opening statement. Sources told CNN on Thursday that Morrison was involved with discussions to move the call to the more secure system.
Eisenberg and National Security Council lawyer Michael Ellis have both been requested to testify in the House's impeachment inquiry on Monday behind closed doors. It's not clear whether either will appear.