The impeachment hearings have begun. The star witness in the first round was undoubtedly acting Ambassador to Ukraine William Taylor, who discussed witnessing President Trump's corruption in that country.

Taylor's testimony was quite long, running to 20 printed pages, and the story he told was somewhat complicated. Nevertheless, the basic through-line is not at all hard to understand. He testified that Trump attempted to blackmail Ukraine into smearing his top political rival, Joe Biden, by withholding military aid.

To start with, when Taylor first took the job, Secretary of State Mike Pompeo assured him the U.S. policy of supporting Ukraine against Russia — which had straight-up annexed Crimea and invaded eastern Ukraine — "would continue and that he would support me in defending that policy." And that was official U.S. policy as carried out through the traditional diplomatic apparatus.

But Taylor gradually discovered a sort of shadow foreign policy, conducted by Trump administration officials through back channels. First, he realized people close to Trump were trying to dangle a meeting between newly-elected President Volodymyr Zelensky and Trump to get Ukraine to investigate the Biden family (through Burisma Holdings, the energy company where Hunter Biden held a board seat) and validate the crackpot conspiracy theory that Democrats framed Russia for meddling in the 2016 election and that some Ukrainians had the evidence. Then Taylor learned that Trump's people were holding up promised military aid as well, for the same reason.

Diplomatic officials told Taylor that acting Chief of Staff Mick Mulvaney had placed a hold on the aid (which had incidentally been legally authorized by Congress and Trump himself). After the aid was kept on hold for over a month, leading to increasing frustration and confusion both in the Ukrainian government and the U.S. diplomatic corps there, Taylor finally got the full story from U.S. Ambassador to the E.U. Gordon Sondland (a major Trump donor, not a professional diplomat) on Sept. 1.

According to Taylor, Sondland told him "that President Trump had told him that he wants President Zelenskyy to state publicly that Ukraine will investigate Burisma and alleged Ukrainian interference in the 2016 U.S. election … He said that President Trump wanted President Zelenskyy 'in a public box' by making a public statement about ordering such investigations."

Sondland lamely attempted to convince Taylor this wasn't an extortion scheme (that is, there were "no quid pro quo's"), but immediately undercut himself in a later call. "During our call on Sept. 8, Ambassador Sondland tried to explain to me that President Trump is a businessman. When a businessman is about to sign a check to someone who owes him something, the businessman asks that person to pay up before signing the check." You don't have to be conversant in mafia codes to get what he is talking about here.

So far this had all been reported before — but Taylor provided an additional piece of damning evidence. While he was at the conflict zone with the Ukrainian military, one of his staffers was with Sondland at a restaurant while he made a call to Trump. "The member of my staff could hear President Trump on the phone, asking Ambassador Sondland about 'the investigations.'" Later, the staffer "asked Ambassador Sondland what President Trump thought about Ukraine. Ambassador Sondland responded that President Trump cares more about the investigations of Biden, which Giuliani was pressing for." Presumably Sondland and that staffer will testify before the committee soon.

All this is a perfect illustration of what allowing Trump-style corruption to completely saturate the American state would entail. The whole dispute between Russia and Ukraine was partly sparked off by diplomatic bungling from the U.S. and the E.U., which have loudly proclaimed their support for Ukrainian independence but repeatedly left it in the lurch. Nevertheless, there is still some semblance of a rational, legal diplomatic structure there — one that better leadership might turn towards more humane and competent ends.

Trump, by contrast, views the entire diplomatic machinery, all foreign countries, and the United States itself, in purely instrumental terms. He has an essentially gangster approach to international relations in which the only relevant questions are how he personally can profit. A fully Trumpified U.S. would drastically worsen America's treatment of other nations, as all traditional diplomatic restraints would be shredded, and the whole diplomatic corps would effectively become agents of the Trump Organization and his re-election campaign.

Finally, once again it is worth mentioning that other things Trump has done are just as bad as his attempt to blackmail Ukraine into interfering in the 2020 election — like his violently unconstitutional profiteering off the presidency. But the Ukraine story is still genuinely bad, and we should be very clear about what happened. The Republican propaganda machine can't obscure Trump's monumental corruption.