It is the scandal which has electrified Washington, New York, and Russia, overshadowed the president's visit to France - and painted his eldest son as at very least a fool and at worst a knave.

The disclosure that Donald Trump Jr met a Russian lawyer after being offered incriminating information about Hillary Clinton is the most scandalous - and possibly most dangerous - yet to hit the White House.

But what is still unknown is who leaked the fact of the meeting and, even worse, the explosive emails between the president's son and the portly British Svengali who offered the dirt on Hillary.

So who started plunged a knife into Don Jr by starting Spygateski - and who has means, motive, AND opportunity?

WAS IT JARED KUSHNER?

Family affair: The president's son-in-law is getting less flack for the Russia meeting than Don Jr - so could that mean he got it out there himself? He was grinning and relaxed at the Sun Valley, Idaho, get-together for billionaires. And family feuding is the Kushner way

THE MEANS: HE WAS SENT THE MEETING EMAIL

To be able to leak the fact of the meeting and the emails means firstly knowing about the meeting, and secondly having the emails.

Jared Kushner had both: he was at the meeting, and he was copied in on the emails setting it up.

What would point more powerfully towards the president's son-in-law is the timing of this.

The reason the meeting came onto any radars at all was because of Kushner's security clearance process.

Details of that were revealed Friday by Yahoo News - with the crucial detail that it was Kushner's lawyers who discovered the emails.

Although it is unclear exactly when they found them, Kushner updated his security disclosure form on June 21 as a result of the emails.

It emerged Friday that his legal team had told Trump's personal lawyer and the attorney for the Trump Organization three weeks ago about the existence of the emails.

That means he had been reminded recently of their existence and had them at hand.

THE MOTIVE: THE BEST DEFENSE IS ATTACK

Donald Trump Jr is family - so what on earth would make Jared Kushner leak the most damaging information yet to hit the White House?

The most plausible explanation is that the White House is a kill or be killed environment and that Jared's camp were calculating that the meeting would emerge in some form anyway - so better to get the focus on Donald Jr than on Kushner.

There is no doubt that if that was the intention, it has succeeded.

The very first headline, in the New York Times on Saturday 8 July, concentrated on Donald Trump Jr, setting the tone for a week of coverage.

He's taking dthe heat: Don Jr went on Hannity to explain himself; sources claim an operation in the West Win is protecting Jared

It was Don Jr, not Kushner, who featured in headlines and on Chyrons, and it was Don Jr who changed his explanation repeatedly, went on Fox News's Hannity show on Tuesday to claim he had told 'everything' only for the list of attendees to grow to include a Soviet spy by Friday.

And there are now claims of an operation to 'protect Jared' inside the White House.

'Who do you have to protect, You have to protect the guy who filled out the form saying I never took this meeting,' said an unnamed source.

The downside to the theory that it is Kushner is that the Trump family have in the past always been utterly united.

But Kushner's family is different: when Charles Kushner, Jared's father was under investigation for making illegal campaign contributions, his own brother-in-law co-operated with federal investigators.

In revenge, Charles Kushner hired a prostitute to seduce his brother-in-law and sent a tape of the encounter to Esther, the man's wife - and Charles's sister - to stop her testifying in an intra-family civil suit. Charles went to prison for witness tampering.

Meanwhile Charles and Jared's uncle Murray are entirely estranged thanks to a 'Cain and Abel' feud which saw them donate to political rivals.

If there are two lessons for Jared, it's that loyalty inside family counts for nothing and that striking first is the best plan - and if that is true, it is now Don Jr paying the price.

THE OPPORTUNITY: IMMACULATE MEDIA CONNECTIONS

The recipients of the leaks so far have been the New York Times, the Washington Post, and NBC. Kushner is hardly short of links to all three.

Kushner, a former newspaper owner, has rarely spoken on camera but he is known to speak to journalists individually and to obsess about his press coverage to the extent that he has his own spokesman, Josh Raffel.

That spokesman had worked in the past for the immaculately connected Hiltzik PR agency in New York.

Jared is thought to have his own contacts among journalists and the extent of his obsession was hinted at by Politico on Friday: he was so irritated at television coverage he wanted two White House staffers devoted to complaining about the contents of cable news channels' kyrons.

So could he have crafted a deal with the New York Times, Washington Post and NBC to make sure they were nice to him?

ANALYSIS

Probably frontrunner for the leaks candidate; no smoking gun yet - but a grand deal with the media seems a conpsiracy theory too far.

WAS IT THE RUSSIANS?

Rich new cast of characters: Rob Goldstone (left) set up the meeting and Rinat Akhmetshin (right) was there. Could their ultimate bosses - probably the Kremlin - be behind the leak?

THE MEANS: OLIGARCH'S SON'S AIDE SET UP MEETINGS

The email trail started by Rob Goldstone would have been in the portly British PR's records - and he is employed by a would-be Russian pop star with deep ties to Putin.

All a Russian operative had to do was hand over first the fact of the meeting and then the emails, which were dripped out, with the New York Times disclosing the existence of the meeting on Saturday, and finally saying it had the emails on Tuesday, which prompted Don Jr to tweet them anyway.

Plenty of Russians knew about the meeting. Among them, we learned Friday, Rinat Akhmetshin.

THE MOTIVE

One motive for the Russians could be unhappiness at progress with the Trump administration.

Although Trump has sounded friendlier and met Putin, in reality sanctions are still in place and could get tougher thanks to laws being pushed by Republican Russia hawks.

The Russians may see this as a black op designed to get the White House to do its bidding - although if that is the case, it might have gone about it the wrong way.

The other possibility is that Russian interventions in foreign adversaries' affairs are often designed with one end: chaos.

In the chaos, Russia's interests are advanced, goes the theory.

That explanation has been offered for the alleged hacking of the 2016 election, with the view being that Putin did not want Trump to win so much as to discredit Hillary Clinton when she got into office.

Now with Trump in the White House, he is trying for the same, paralyzing the administration with this leak, and the possibility of more to come.

THE OPPORTUNITY

The way in which the story emerged raises some eyebrows.

For a group of shadowy figures, the Russians at the meeting have been surprisingly loquacious.

Indeed it only took from Saturday until Tuesday for NBC News to be sitting down exclusively with Natalia Veselnitskaya in their Moscow bureau.

One eyebrow-raising point is that their correspondent Keir Simmons must have been issued a visa to get into Moscow - and if he did not have a pre-existing one, they usually take days to be processed.

A second eyebrow might be raised by the way NBC News reported the presence of an 'unnamed man' on Friday morning, who was quickly revealed to be Rinat Akhmetshin.

Giving a source anonymity is standard journalistic practice to be able to get access to a story.

So could the lobbyist - who was paid hundreds of thousands of dollars to get legal measures the Russians hate overturned - have been NBC's source?

ANALYSIS

Russians like causing chaos but this would seem to make it more, not less, likely that they get hit by sanctions.

WAS IT THE FBI?

Served cold? James Comey's old agency might have been passed the means to epicly shiv its enemies- the Trumps and Jared Kushner, who pushed for him to be fired

THE MEANS: THEY INTERVIEWED JARED LATE IN JUNE

The FBI were told the fact that Kushner met the Russians on June 21 when he updated his SF-86 security clearance form to disclose that and many other meetings.

it is unclear whether he would have had to provide supporting documentation to them for the newly-disclosed meetings when updating the form.

But until Friday it had not been appreciated that this was followed on June 23 by the FBI interviewing Kushner.

That raises the significant possibility that the FBI were given - or demanded - the emails which revealed the meeting, putting in their hands the explosive information they contained.

THE MOTIVE: REVENGE STRIKE - OR CLEVER DETECTIVE WORK

The FBI has just been through the shattering firing of its director, James Comey, because of the Russia probe.

And the man who pushed for it inside the White House was Jared Kushner.

The role was first reported in May by the New York Times, which disclosed that others argued against sacking him

Comey was widely-reported to be popular inside the FBI and if agents were presented with a smoking gun which discredits not just Trump but Kushner particularly, then it would have been a powerful incentive to leak.

That went well: Jared argued to fire Comey, Bannon argued against - now Jared is the one being questioned by the Feds

But there could be a less personal and more professional explanation too: that the FBI decided to plant a strategic leak to flush out more details.

While they knew about the meeting once they got Kushner's form, they still didn't know a lot about it.

Thanks to the tsunami of revelations which have followed the disclosure, FBI agents now have a rich seam of people to investigate - and a lie to hold over Don Jr's head.

While failing to tell the truth to Sean Hannity is not a federal offense, Don Jr might be a more pliant and talkative witness now that the meeting is known.

And Russians who would be unlikely to co-operate with the FBI have given damaging evidence in public.

So could the FBI have advanced Robert Mueller's probe into alleged Trump-Russian collusion with a single explosive leak?

It is a highly-risky tactic for an agency already reeling from the Clinton server investigation, and the sacking of James Comey. But if it works, it would be worth it.

THE OPPORTUNITY: AGENCY HAS LEAKED BEFORE

Deep Throat was the deputy FBI director and James Comey told the Senate that he leaked as soon as he was out of office, so the FBI isn't exactly new to leaking.

The Times, Post and NBC all have reporters with deep connections to law enforcement.

What is simpler than an old-fashioned document drop? One intriguing point is that after Don Jr published his emails, the New York Times did not publish their versions - which might have some more features on them to identify how they emerged; Don Jr's of course were simply printed from his inbox, scanned and tweeted.

The problem with blaming the FBI of course is that it is usually more interested in prosecuting in the law courts than in the court of public opinion.

ANALYSIS

Revenge is a dish best served cold - and the FBI may have in its ranks someone who remembers the words of Jim Malone to Eliot Ness in the Untouchables: 'He pulls a knife, you pull a gun. He sends one of yours to the hospital, you send one of his to the morgue.'

A strategic leak in the highest-profile investigation the agency has had since the Clinton probe seems like a huge risk for the FBI - but on the other hand, if it discovered evidence of collusion, it would be the biggest win in its history.

WHO ELSE COULD IT BE?

Et tu dad? Could Trump himself have thrown his own son - who he called a 'good kid' under the bus?

Trump's White House is more like Game of Thrones than the West Wing.

The feuding camps are now lined up so that Steve Bannon and Reince Priebus are on the opposite side from Jared Kushner - at least for now.

All of them speak to reporters on and off the record regularly.

High-powered team: Trump's personal lawyer Marc Kasowitz is there to protect one man: the president

Outside are legal teams who have had access to the information.

One is representing President Trump alone. He could have decided to throw his son under the bus because so far this scandal does not implicate him directly.

Or one of his legal team could have made that calculation on his behalf - or equally the legal team could itself be compromised by a malicious leaker.

Also around inside the White House are long-time officials who may be honest whistleblowers or smear merchants - depending on the view of the person describing them.

Obama holdovers always get a mention when the White House is trying to find the source of leaks.

And there is the 'deep state' outside the White House, the shadowy spy community which the Trump camp claim is trying to bring them down.

And finally there is the possibility of a completely different figure - perhaps even the 400lb hacker in his mom's basement who Trump suggested might have hacked the DNC.

ANALYSIS

This story gets crazier by the day, so why not?