In the hours and days after the Ukrainian President signed-off -- "Thank you Mr. President, bye-bye" -- nervous word spread among national security aides about the contents of the July 25 call, an early show of worry that Trump's request for an investigation into Joe Biden was far from the "perfect" conversation he now insists transpired.

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At least one National Security Council official alerted the White House's national security lawyers about the concerns, three sources familiar with the matter said, a detail that had not been previously disclosed. Those same lawyers would later order the transcript of the call moved to a highly classified server typically reserved for code-word classified material.

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Unsettled aides also immediately began quizzing each other about whether they should alert senior officials who were not on the call -- mainly those at the Justice Department, since Trump had invoked the agency's boss, Attorney General Bill Barr, multiple times during the 30-minute talk.

White House lawyers, aware of the tumult, initially believed it could be contained within the walls of the White House. As more people became aware of the conversation -- and began raising their internal concerns about it -- a rough transcript of the call was stored away in a highly classified server that few could access.

The order to move the transcript came from the White House's national security lawyers to prevent more people from seeing it, according to people familiar with the situation. It also came after recognition the document would need to be preserved for legal reasons.