AP
Washington, Nov : 20 Two top national security aides who listened to President Donald Trump’s call with Ukraine are preparing to testify in the impeachment hearings, launching a week of back-to-back sessions as Americans hear from those closest to the White House.

Lt. Col. Alexander Vindman, an Army officer at the National Security Council, and Jennifer Williams, his counterpart at Vice President Mike Pence’s office, both say they had concerns as Trump spoke on July 25 with the newly elected Ukraine president about political investigations into Joe Biden.

After they appear Tuesday morning, the House will hear in the afternoon from former NSC official Timothy Morrison and Kurt Volker, the former Ukraine special envoy.
In all, nine current and former U.S. officials are testifying in a pivotal week as the House’s historic impeachment inquiry accelerates and deepens. Democrats say Trump demanded that Ukraine investigate his Democratic rivals in return for U.S. military aid it needed to resist Russian aggression and that may be grounds for removing the 45th president. Trump says he did no such thing and the Democrats just want him gone.

“I did not think it was proper to demand that a foreign government investigate a U.S. citizen,” said Vindman, an Iraq War veteran. He said there was “no doubt” what Trump wanted from Ukrainian President Volodymyr Zelenskiy.

It wasn’t the first time Vindman, a 20-year military officer, was alarmed over the administration’s push to have Ukraine investigate Democrats, he testified.
Earlier, during an unsettling July 10 meeting at the White House, Ambassador Gordon Sondland told visiting Ukraine officials that they would need to “deliver” before next steps, which was a meeting Zelenskiy wanted with Trump, the officer testified.

On both occasions, Vindman said, he took his concerns about the shifting Ukraine policy to the lead counsel at the NSC, John Eisenberg.
Williams, a longtime State Department official who is detailed to Pence’s national security team, said she too had concerns during the phone call, which the aides monitored as is standard practice.
When the White House produced a rough transcript later that day, she put it in the vice president’s briefing materials. “I just don’t know if he read it,” Williams testified in a closed-door House interview.

Sondland, the wealthy donor whose routine boasting about his proximity to Trump has brought the investigation to the president’s doorstep, is set to testify Wednesday. Others have testified that he was part of a shadow diplomatic effort with the president’s personal lawyer, Rudy Guiliani, outside of official channels that raised alarms.

Pence’s role throughout the impeachment inquiry has been unclear, and the vice president’s aide is sure to be questioned by lawmakers looking for answers.
The White House has instructed officials not to appear, and most have received congressional subpoenas to compel their testimony.

Trump has already attacked Williams, associating her with “Never Trumpers,” even though there is no indication the career State Department official has shown any partisanship.
The president wants to see a robust defense by his GOP allies on Capitol Hill, but so far so far Republicans have offered a changing strategy as the fast-moving probe spills into public view.