But I'll be focusing on how the US has manipulated Ukraine. Starting in 2016, it seems like the Hillary campaign went to the EU/US aligned government (the successor to the ousted Russian-aligned government) and got information that was harmful to Paul Manafort, the campaign chairman for Trump. They also helped with the Mueller investigation.
That's two strikes, especially if you're as vindictive as Trump is. However, Ukraine has lots of backers in Congress, and some in executive branch, but it seems like Trump was not going to be at all sympathetic. Trump did have the problem of looking too pro-Russian, and he figured a way to counter that. He'd give weapons to Ukraine, which is something Obama was very cautious about due to the unintended consequences of wars spreading and weapons being used in unforeseen ways.
So Trump gave Ukraine weapons, and got himself some talking points. He also got some things he didn't talk about. Ukraine stopped working with the Mueller team, shutting down all cooperation. This was back in April 2018.
The Poroshenko government starts playing nice with the Trump administration. But there's trouble in Ukraine, where corruption is rampant and unpopular. Poroshenko is voted out in April 2019, and a new government by a comedian is in. The Trump administration doesn't know if the new government will play ball the way the Poroshenko government learned to do,
Leaning on the New Government
With this background, it's not hard to understand the phone call. Zelensky, the new Ukrainian president, is kissing up as hard as he can, It starts with Zelensky saying how Trump's surprise electoral win inspired his own win, and a mention of draining the swamp. Major sucking sounds from Zelensky, but what choice was he have? Zelensky is very eager to conduct whatever investigation Trump asks for, and even asks for additional information from the US that won't be helpful. Is that a coded way to ask Trump what he wants them to say?
On the other hand, he makes no promises about who his new chief prosecutor would be, even after Trump says that the last one was very good and very fair. When you read below about the chief prosecutors, you have to wonder if anyone fits that description.
The two prosecutor to be aware of are Shokin and Lutsenko. Shokin was the corrupt prosecutor in 2016 whom Biden, the EU, and the IMF forced out. Supposedly he was investigating Hunter Biden at Burisma, a gas company, but most reports say that the investigation was not ongoing.
Lutsenko was a real piece of work. He was the chief prosecutor under Poroshenko, and he lost his job when Poroshenko lost reelection. (Hmmmm, lost reelection... that sounds good.) Lutsenko accused the US ambassador of giving him a list of people and companies who couldn't be investigated or charged. But it was all a lie. That gives a sense of the ethics of this guy. It seems possible to me that both Giuliani and Trump were pushing Zelensky to re-instate him. It's no wonder since he was probably playing ball with the Trump administration, taking their direction to stop cooperating with the Mueller investigation and who knows what else. He seems to have been a good toady (to Trump) who lost his job due to Ukrainian public dissatisfaction and 'voting the crooks out.'
The most important ambassador is Marie Yovanovitch. She is the one Trump mentioned disrespectfully. Lutsenko accused her of interfering and ordering him not to investigate people, and she was removed by Trump for not playing ball. She's a career diplomat, well versed in Slavic countries, and well respected by her colleagues according to reports. Perhaps she's too professional, especially when the prez wants his personal lawyer to tell a country that they should investigate his personal political rival. Basically, she was stabbed by Trump and his dog pack.
Other ambassadors. Volker Volker resigned.
Sondland. More serious than Trump's usual backers.
What will the Ukrainian government do now that the pressure is no longer covert? It seems to me that the Ukrainians can make their own choices. They have enough supprt from Americans and in Congress that Trump can't put the screws on them again. Relations between the US and Ukraine will be closely scrutinized. Giuliani's travel will be closely scrutinized. Trump and Giuliani's plans - simply screwed. Such poetic justice in that.
Funny bits: President Zelensky has won a not-so-nice nickname in Ukraine: Monica Zelensky. Oooh, burn. But he's also helped shine a light on the cockroach named Trump.
Giuliani is spinning like mad. He's trying to indicate that he had State Department backing, but that doesn't help the State Department look good. It just shows how many people didn't feel they could push back from Trump's vendetta. However, Giuliani may have his own vendetta against Biden. For one thing, Biden landed a punch against Guiliani during Giuliani's campaign for president. 'Every sentence he says has a noun, a verb, and 9/11.' It was quite a takedown.
Recap: A who's who from CNN. A bunch of lies from an opinion writer at Fox, including the statement (as though it's fact) that Joe Biden received over $1 billion in bribes from China.
Update 10/3/19. Texts among State Departnment personnel and others show that Ukraine was being squeezed, though they were careful not to put the most damning info into texts.
Update 10/23/19. Lots of state department folks are testifying in the House. The replacement for the ousted ambassador was particularly searing. Trump called the guy a 'never-Trumper' and doesn't want to hire anymore like him. Maybe he wants clear loyalty (echoes of what Comey reported). In another (unraveling) angle, Giuliani was working with some rather unsavory characters, and probably even more still to be uncovered and possibly indicted.
Update 10/24/19. More details. Trump wanted the Ukrainians to publicly announce investigations as a sign of their strong commitment. Plus this tidbit: two dozen House GOPers tried to storm a closed hearing, and complain about it being secret. But Trey Gowdy, a former House GOPer and future lawyer to Trump, is on video saying how open hearings are useless, while private hearings are effective.
Update 11/7/19. More about the feud between Giuliani and Biden. When it might have started--from a journalist who isn't exactly a friend of Giuliani. Giuliani insulting Biden in 2012. Biden's quips about Giuliani are lost, but there is a bit of context to help the imagination.