It’s a relatively slow news day, so it might be worthwhile to attempt an explainer at something that’s probably going to feature a lot in American news over the next few months as we barrel towards the quadrennial carnival of stupidity that is an American Presidential Election:

What’s the background to this? What’s it all about? Well, you might remember this story from the Irish Times from the early days of the Trump Presidency:

Donald Trump’s national security adviser has been in regular contact with Russia’s ambassador to the United States, it emerged on Friday, as the controversy around the president-elect’s ties to Russia showed no signs of abating.

The White House is aware of phone calls between retired lieutenant-general Michael Flynn and ambassador Sergey Kislyak, a senior US official told the Associated Press.

It is not clear how the current administration learned of the contacts, although the AP noted that US monitoring of Russian officials’ communication within the US is known to be common.

The disclosure came after a week dominated by the release of a dossier, prepared by a former British intelligence officer, alleging that Russia had collected compromising information about Mr Trump and that there had been secret communications between them. The president-elect fired off a fresh round of tweets about the Russian connection that continues to overshadow the build-up to his inauguration a week from now.

Pay attention to that part in bold. It’ll become important in a minute.

Anyway, that revelation led directly to Flynn resigning as National Security Advisor, on the perfectly reasonable grounds that it’s not ideal if the top security person in the White House is having cosy chats with the Russians without the President knowing about it.

In fact, Flynn was subsequently prosecuted by the FBI, and prosecuted by Special Counsel Robert Mueller, who, you might recall, was in charge of the investigation into supposed Russian collusion with the Trump campaign in 2016.

Flynn (and this is an uncomfortable fact in this story for Trump fans) made a plea bargain, admitting that he had lied to the FBI about his contact with the Russians:

“TV cameras swarmed a federal courthouse on Friday to witness former national security adviser Michael Flynn arrive to plead guilty to a felony count of lying to the FBI about conversations he had with then-Russian ambassador Sergey Kislyak. The stunning news comes only a month after a federal grand jury indicted two top Trump campaign staffers—Paul Manafort and Rick Gates—on charges related to their foreign lobbying work, while lower-level aide George Papadopoulos also pleaded guilty to lying to the FBI.

Flynn is now cooperating with special counsel Robert Mueller’s investigation, and the court documents say he had called Kislyak on the orders of an unnamed senior transition official.”

At the time (and this is an uncomfortable memory for fanatical Trump opponents) there was great excitement about the bit in bold, because the idea of Flynn co-operating with the investigation into Trump was supposed to be the crack in the case that would finally bring the President and his whole (in the eyes of his critics) criminal enterprise down.

But of course, it didn’t work out like that. Even with Flynn’s co-operation, the FBI and Mueller were unable to show any level of supposed “collusion” between Trump and Russia at all.

And when Mueller delivered his report to Congress, everything went quiet for a while, until January of this year, when Flynn suddenly withdrew his guilty plea, alleging bad faith by the Government (Government in this case meaning the prosecution, not the US federal government):

“Former national security adviser Michael Flynn — the only Trump administration official to face criminal prosecution in special counsel Robert Mueller’s investigation — is seeking to withdraw the guilty plea he offered more than two years ago to a charge of making false statements to the FBI.

The move, made just two weeks before Flynn is supposed to face his long-delayed sentencing, follows Flynn’s shift to more confrontational defense lawyers about half a year ago and an ensuing, acrimonious showdown with prosecutors over the retired Army general’s planned testimony in a related case.”

It’s important, again, here, to note: Flynn is not now denying that he lied to the FBI. That bit of the case is undisputed. What he’s alleging, if you read the full story, is that prosecutors mislead him about the sentence he could expect to receive, and also – and this is where we finally get to the “Obamagate” part – that prosecutors targeted him maliciously, and for political reasons.

Then, last week, the US Department of Justice made a stunning announcement:

The Justice Department dropped its case against former Trump national security adviser Michael Flynn—though Flynn had pleaded guilty twice to charges—saying the FBI’s counterintelligence investigation of Flynn was “untethered” and “unjustified,” according to documents obtained by the Associated Press.

The choice of words there, again, is important: They’re not saying Flynn didn’t do it. They are saying that the prosecution was “untethered and unjustified”, which suggests that it was – in their view – at least in part politically motivated.

And then, last week, President Obama himself, not somebody who’s been especially prone to political interventions since he left office, had this to say:

“Obama has largely held his tongue about the actions of his successor but on Friday in a call to 3,000 former aides and officials that was leaked to the media, he let loose.

“There is no precedent that anybody can find for someone who has been charged with perjury just getting off scot-free,” he said. “That’s the kind of stuff where you begin to get worried that basic – not just institutional norms – but our basic understanding of rule of law is at risk.”

Trump, who has never been shy about criticising – or blaming – his predecessor, responded with a flurry of social media posts and retweets on Sunday, accusing Obama and his aides of engaging in a criminal effort to undermine his presidency.”

On the one hand, Obama’s frustration is understandable: After all, Flynn did lie to the FBI. Nobody disputes that. On the other hand, says the Wall Street Journal, it was very, very odd:

“Barack Obama is a lawyer, so it was stunning to read that he ventured into the Michael Flynn case in a way that misstated the supposed crime and ignored the history of his own Administration in targeting Mr. Flynn. Since the former President chose to offer his legal views when he didn’t need to, we wonder what he’s really worried about.”

And now, finally, we get to the crux of it: The evidence is overwhelming that the investigation into Flynn was started by the Obama administration during the 2016 election. More from the Wall Street Journal:

“All of this raises questions about the role the Obama Justice Department and White House played in targeting Mr. Flynn. We already know the FBI had opened up a counterintelligence probe into Mr. Flynn and other Trump campaign officials, yet it had come up with no evidence of collusion.”

Donald Trump’s victory increased the chances that this unprecedented spying on a political opponent would be uncovered, which would have been politically embarrassing at the very least. Targeting Mr. Flynn—and flogging the discredited Steele dossier—kept the Russia collusion pot boiling and evolved into the two-year Mueller investigation that turned up no evidence of collusion.

This among other things is what U.S. Attorney John Durham is investigating at the request of Attorney General William Barr. Maybe that’s why Mr. Obama is so eager to distort the truth of the Flynn prosecution.”

And there you have it: The accusation is that Obama’s administration ordered a politically motivated investigation into a senior Trump campaign official at the height of the 2016 Presidential election. If this were to be true, it would, obviously, be a monumental scandal, on a par with Watergate (everyone remembers Nixon’s dirty tactics, but few remember that those dirty tactics uncovered legitimate scandals about his opponents that they were trying to keep hidden).

In some senses, it doesn’t really matter that Flynn lied to the FBI if those lies were uncovered by an abuse of Government power. Politicians, after all, cannot order investigations of their opponents. If Trump himself were accused of the same thing, it would be a massive scandal also.

Of course, at the moment, it’s just that – an accusation of a scandal. And, it’s important to remember, the present Department of Justice is controlled by Trump, and has the same incentive to investigate Obama as Obama’s people had to investigate Flynn.

But this is what it’s all about – did Obama (to quote everyone’s favourite movie) order the Code Red on Mike Flynn?

We may never know. But it’s going to feature an awful lot in the Presidential Election, since Obama’s Vice President, Joe Biden, is taking on Trump.

They might talk about other things too, I suppose, like taxes and health and foreign policy. But don’t count on it. It’s an American election, after all.