President Donald Trump’s latest and greatest scandal centers on a key decision: his suspension of US military aid to Ukraine.

The Eastern European nation was expecting nearly $400 million in US support — including weapons, training, and advisers — to boost its effort to fight off Russia which invaded the country in 2014.

But by the time Ukrainian President Volodymyr Zelensky got on the now infamous July 25 call with Trump, that aid had yet to be sent. It’s therefore no surprise Zelensky mentioned the assistance to Trump, to which Trump responded he’d like Zelensky to do him a “favor” in return: investigate former Vice President Joe Biden and his son.

It certainly seems like a quid pro quo was pretty clearly implied: You want your aid? Help me dig up dirt on my 2020 political rival.

Trump, however, continues to plead his innocence on Twitter by claiming nothing improper happened on the call.

“IT WAS A PERFECT CONVERSATION WITH UKRAINE PRESIDENT!” — Donald J. Trump (@realDonaldTrump) September 27, 2019

Which means much of the current drama threatening Trump’s presidency comes down to this: Exactly why was the military aid held up in the first place?

What we know is already damning.

There seems to have been a lot of obfuscating about military aid to Ukraine

The $391 million in military aid to Ukraine had already been approved in the 2019 federal budget. It was meant to bolster Ukrainian forces in their ongoing conflict against Russian invaders in the country’s east and included money for arms and radar systems as well as funding for naval forces and NATO aid.

The Trump administration initially told Congress it was releasing the aid to Ukraine on February 28. It repeated that assertion to Congress again on May 23, but failed to explain to lawmakers but struggled to explain — both publicly and to the lawmakers who approved the aid — exactly why the funds were withheld.

Even Senate Majority Leader Mitch McConnell couldn’t get a straight answer from Secretary of State Mike Pompeo and Defense Secretary Mark Esper over the summer on why the aid hadn’t been dispersed yet.

But then on September 11, the Trump administration suddenly disbursed the money.

So what changed? It’s not entirely clear.

Senate Republicans immediately said it happened because Sen. Dick Durbin (D-IL) threatened to block $5 billion in Pentagon spending for 2020 if the aid wasn’t sent.

The next day, GOP members of the Senate Appropriations Committee said the assistance had been held while the White House assessed whether Zelensky, who came to power in May, was aligned with the US and NATO over Russia. That was an odd argument, since one of Zelensky’s main electoral platforms was combating Moscow and ending the war.

But thanks to reports in the Washington Post and New York Times this week, we now have a little more information.

Mick Mulvaney, the dual-hatted acting White House chief of staff and director of the Office of Management and Budget, told leaders at the State Department and Pentagon in mid-July that Trump wanted the money withheld because he had “concerns” about the aid’s necessity. Those departments were instructed to inform members of Congress with questions about the delay that the money was coming but that its disbursement had been held up by “interagency process.” Those questions did come, but lawmakers received little information.

That timing is important, since Mulvaney’s announcement came about a week before Trump and Zelensky spoke on the phone. What makes matters worse, some say, is that the directive came from the president himself — meaning Trump may have used the new delay as leverage to extract something from his Ukrainian counterpart.

Trump has changed his story about why he personally withheld the military support at least twice. On Monday, Trump told reporters that his decision was due to concerns about corruption in Zelensky’s new government. But asked a similar question on Tuesday, Trump’s talking point suddenly changed: now he said he’d withheld the aid out of frustration that European countries were not doing enough to support Ukraine themselves.

“My complaint has always been, and I’d withhold again, and I’ll continue to withhold until such time as Europe and other nations contribute to Ukraine, because they’re not doing it,” Trump told reporters ahead of his speech to the United Nations General Assembly.

The change from Monday to Tuesday was captured in this clip put together by CNN.

Wow -- CNN put together this clip highlighting how Trump changed his public rationale for withholding aid to Ukraine from yesterday to today pic.twitter.com/25QJ8VPsnU — Aaron Rupar (@atrupar) September 24, 2019

Ukraine, meanwhile, has tried to stay out of it. Ahead of Zelensky’s meeting with Trump at the UN this week, the Ukrainian president told the press that he doesn’t want to interfere in US domestic politics.

Put together, it’s still unclear just why Trump delayed the nearly $400 million in military assistance. Defenders say Trump has long questioned why the US spends money on others’ defenses, while critics argue he conveniently used it as leverage so Zelensky would “do us a favor,” as the White House call summary shows the president saying.

The critics’ argument is bolstered by one thing in particular: Trump’s obsession with having Ukraine look into Biden’s family.

Why Trump wanted Ukraine to investigate Biden, briefly explained

The exchange at the middle of Trump’s call with Zelensky centers on Joe Biden’s role in efforts to remove Ukraine’s top prosecutor, Viktor Shokin, in 2016. Trump and his allies have asserted — without any evidence — that Biden’s participation in Shokin’s ouster was itself corrupt and specifically that it was aimed at protecting his son Hunter.

At the time, Hunter Biden was on the board of a company, Burisma, whose owner was under investigation for corruption and money laundering. Shokin was believed to be hindering that investigation and anti-corruption investigation in Ukraine more broadly. This was frustrating the Ukrainian executive branch, the US, international finance officials, and some NATO allies — all of which had stakes in a corruption-free Ukraine, given the civil and military aid some were funneling to the country to help it fend off Russian aggression.

So in 2016, Biden told the Ukrainian government that their loan guarantees would be cut off unless they removed Shokin. He told the story at a session at the Council on Foreign Relations in 2018.

“I said, ‘You’re not getting the billion.’ I’m going to be leaving here in, I think it was about six hours,” Biden said. “I looked at them and said: ‘I’m leaving in six hours. If the prosecutor is not fired, you’re not getting the money.’”

The former vice president said after the threat, “Well, son of a bitch, he got fired. And they put in place someone who was solid at the time.”

Though Biden may have taken credit for it, this was hardly his unique idea. “Everyone in the Western community wanted Shokin sacked,” Anders Aslund, a senior fellow at the Atlantic Council, told the Wall Street Journal. “The whole G7, the IMF, the EBRD, everybody was united that Shokin must go, and the spokesman for this was Joe Biden.”

So despite his boast last year, Biden seem to have played a very minor role in Shokin’s firing. Within the Obama administration, the idea to remove him came from the US’s embassy in Ukraine, and the sentiment the prosecutor was hindering anti-corruption efforts was shared by the US’s partners and Ukrainian citizens.

Nevertheless, Trump maintains Biden personally had Shokin fired in order to protect Hunter from criminal liability. This does not make a lot of sense considering the removal of Shokin had the potential to hurt Hunter, given the US hoped to replace the prosecutor with someone more fully committed to pursuing an anti-corruption agenda.

Biden himself has called the accusation false and has said Trump concocted it to distract from the whistleblower investigation: “Trump’s doing this because he knows I’ll beat him like a drum,” Biden said Saturday. “And he’s using the abuse of power and every element of the presidency to try to do something to smear me.”

The question now is if Trump’s abuse of power will be proven without a shadow of a doubt. One way to know for sure would be to uncover exactly why Trump withheld the Ukraine aid in the first place.

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