As the aid was being blocked this summer, Ukraine officials began quietly asking the State Department about the hold-up.
The recent rhetoric from Hurd perhaps best highlights the uphill battle Democrats face in winning over retiring GOP members. She has testified that she was ousted after Mr Giuliani and his allies mounted a campaign against her with what she called "unfounded and false claims by people with clearly questionable motives". "It would be a really big deal in Ukraine, and an expression of declining USA support for Ukraine".
It was the first she had heard of the quid pro quo that is now the central question of the impeachment inquiry - the administration's push for the Ukraine government to investigate Trump's political rivals. He said he would release this week a transcript of an earlier call he had with Ukrainian President Volodymyr Zelenskiy. He's also linked Trump's chief of staff Mick Mulvaney to efforts to coerce Ukraine into a politically motivated investigation.
The first on-camera hearings in the investigation are set for later this week and focused on accusations that Mr Trump improperly withheld security money as leverage to pressure Ukraine to investigate political rival Joe Biden.
The testimony came from Laura K. Cooper, the deputy assistant secretary of defense for Russia, Ukraine and Eurasia, who was deposed under oath last month during a session that was disrupted when House Republicans stormed the secure facility where it was being held. On Wednesday, the House Intelligence Committee takes the impeachment investigation public after six weeks of closed-door depositions from White House, State Department and other officials.
When she and others tried to get an explanation, they found none.
She sought more details from the NSC and State Department, she said, but was unable to get clarification.
"My sense is that all of the senior leaders of the USA national security departments and agencies were all unified in their - in their view that this assistance was essential", said Cooper, an assistant defense secretary. Democrats recognize that the onus is on them to make the case to independent voters who don't have time to sift through thousands of pages of transcripts alleging presidential misconduct.
Croft and Anderson testified about the oversized reach of Trump lawyer Rudy Giuliani into foreign policy on Ukraine in unsettling ways as he portrayed Zelenskiy's new government as an "enemy" of Trump.
He also spoke of an "irregular channel" of policymaking including Giuliani, Energy Secretary Rick Perry, U.S. Ambassador to the E.U. Gordon Sondland and Kurt Volker, special envoy to Ukraine.
"If you go back to 2014, when Ukraine found itself under attack by Russian Federation, the state of the Ukrainian Armed Forces was significantly less capable than it is today, and that capability increase is largely the result of US and allied assistance".
Testimony by Laura Cooper, deputy assistant secretary of defence, was the latest to be made public that showed the internal machinations of the administration as Trump insisted that almost $400 million in aid slated for Ukraine be withheld until its president publicly launch an investigation into one of Trump's top political rivals.
"There were many affirmative statements that the Congress has appropriated this, we need to obligate it", Cooper said of the Ukraine funding, noting there were concerns about a potential violation of the Impoundment Control Act.
According to Taylor, there was a concerted effort by what he referred to as this "irregular, informal channel of USA policy-making" to pressure Ukraine to commit to opening investigations into unproven allegations of Ukrainian interference in the 2016 US election, as well as into the gas company Burisma.
Cooper described the Ukraine Security Assistance Initiative, saying it involved a range of items such as night vision goggles, vehicles, sniper rifles and medical equipment.