When did the Trump administration’s descent into the Ukraine scandal begin? There are plenty of potential starting points, but for Fiona Hill, the Trump National Security Council’s former top Russia staffer, it all began when the axe fell on Masha Yovanovitch, the former U.S. ambassador to Ukraine and the victim of a whispering campaign started by Rudy Giuliani. When Trump fired her, it was a “kind of tipping point or turning point” for the actions that have mired the Trump administration in allegations of a quid pro quo. So how could one ambassador’s ouster pave the road to impeachment?

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The beginning: In testimony released on Friday, Hill said Yovanovitch’s departure was an important pivot point in the Ukraine scandal timeline “because it was after she was removed from her position that you started to see, you know, more of this activity.”