Why would the country's best-selling newspaper (circulation 1.7m) declare war on the country's most popular football pundit (Twitter following 5.3m) over a couple of tweets about refugees from the Calais Jungle?
Because it hates the BBC?
Because it's worried about immigration?
Because it's not that keen on Gary Lineker?
Because it wants to distract attention from the jailing of a former star reporter?
Possibly - probably - all of the above.
But also because it is worried.
The Sun is worried because this week will see the next chapter in the saga that began when its sister paper's reporters started listening in to people's voicemail messages.
A body called the Press Recognition Panel, which has spent £2m of public money over the past two years trying to find something to recognise, at last appears ready to grant its imprimatur to an "independent" press regulator that will conform to the recommendations of the Leveson inquiry.
Impress has been set up with money from motor-racing magnate Max Mosley and encouragement from Hacked Off - both renowned lovers of our tabloid newspapers - and has the backing of the National Union of Journalists.
It does not have the support of publishers of national newspapers, most of which have agreed to be regulated by the Independent Press Standards Organisation, under the chairmanship of Sir Alan Moses. (A couple - the FT and Guardian - have chosen not to submit to regulation by anyone.)
Ipso, also established in response to Leveson, has been up and running for a couple of years and is, according to a recent review by a former senior civil servant, doing an OK job.
Given its rulings on Katie Hopkins calling refugees "cockroaches" and Kelvin MacKenzie's protestations that a woman in a hijab shouldn't read news about terrorism, not everyone would agree, and many people still have qualms about it because it was set up and is funded by the publishers.
That tends to be the way of things with self-regulation - and even those wanting more controls on the Press insist that self-regulation is the preferred option.
Ipso won't seek recognition from the PRP because that was created and financed by the State, and state-backed regulation - even at "arm's length" and with "triple locks" - is anathema.
Now we are about to move from the situation of a recognition panel with nothing to recognise to one of a regulator with no one (apart from a few small publications) to regulate.
If you're not that worried about £2m of public money going down the drain, that might not matter too much. But the chances are that the Government will want to rescue its baby.
For the time being, forget Article 50. The pressing concern for journalists this week is whether Theresa May will trigger Section 40.
For this provision in the 2013 Crime and Courts Act includes the blackmail - an emotive word, but justified - that will require newspapers that decline to accept the authority of a state-recognised regulator to pay all the costs any time they are taken to court. Even if they win.
The idea is to encourage the use of arbirtration rather than the courts to settle complaints, but the implications of such a law - which can be brought into force by statutory instrument because the parliamentary debates have been and gone - for press freedom are self-evident.
There has been some pretty ropy journalism from our national newspapers this year, particularly in the coverage of the referendum and immigration, but there has also been commendable work. Besides the huge sporting scandals, there have been investigations into tax avoidance by big business, sex abuse, charities, terrorism, election spending, religions and family courts - there are more than 50 entries in the investigations section for this year's British Journalism Awards.
Under Section 40, any or all of those could have been strangled at birth by a threat to sue.
Yes, editors have always had to weigh up the potential costs of pursuing a story, but under the proposed regime they will have to consider the greater risk of having to pay legal costs even if they come out on top in court.
(Remember that the phone hacking that started all this was exposed by exactly the kind of investigative journalism that might be thwarted by Section 40 - it takes a lot of time, money and nerve to go after the biggest beasts. It's also worth remembering that it did not require Leveson to bring guilty journalists to justice. There were laws in place, the problem lay in the way the police accepted obfuscation from the people they were supposed to be investigating.)
There is a provision in Section 40 that a judge does not have to enforce the costs rule if it is not "just" - and one would hope that if you proved someone was a lying toerag, a sane judge would find in your favour. SubScribe is convinced that the rule would collapse the first time it was tested in court. But until that happens, the Press can only hope.
No wonder newspapers are squealing. The Times ran a top leader on Thursday headlined "Not impressed" that said the rival regulator could become a vehicle for an unprecedented attack on free speech. The Daily Mail, which fervently wants to Britain to be free of the European Convention on Human Rights, is invoking that very convention in its fight against Section 40. [Monday update: Today it reprints an article by Matthew Parris that first appeared in The Times on Saturday, describing the statute as "cowardly blackmail". The Murdoch papers are in full cry, with the leader and Parris in the Times, the Lineker story in the Sun followed up by a full-drop leader today, and a leader about the PRP replacing one about Putin at the last minute in the Sunday Times.]
Local newspapers, which were blameless in the eyes of Leveson, are particularly worried and many have also carried leaders on the subject.
|The Murdoch papers and the Mail are in full cry|
That is why The Sun took the opportunity to attack a BBC presenter for something he said on unregulated Twitter - hitting two rivals with one stone.
The central concern for the Murdochs, Rothermeres, Barclays and their editors is, of course, commercial (always remember that newspaper publishing is a business, not a public service - proprietors are not obliged to print stuff that people don't want to read). They don't like competitors having an advantage and they want the freedom to print what they like.
As far as competition is concerned, nearly every paper indulges in routine BBC-bashing and leaders demanding that ministers rein in the corporation (they're not so concerned about editorial freedom and state control for the BBC because it is a publicly funded rival). But that's about as much as they can do. There's no way anyone can attempt to regulate the internet.
As to freedom, the ostensible objection to Impress is one of principle - the very notion that the State should have any influence at all, however far removed - and that is hard to argue against. But that battle was lost in 2014.
Even so, while there was no official regulator on the horizon, there was still some hope of winning the war by default. That is about to change.
Come on, I can hear doubters say. They aren't worried about free speech or constraints on their ability to hold the powerful to account; they're scared they're going to be forced to behave.
Well let's park the role of the State (yes, it's the crux of the matter, but bear with me) and ask would it make any practical difference if newspapers were regulated by Impress rather than Ipso?
For the moment, the answer appears to be No. Impress has published a draft code of conduct (currently out for consultation) that is remarkably similar to that employed by Ipso.
Provisions for intrusion, privacy, accuracy all pretty well match Ipso's. Impress would have the right to instigate investigations without a complaint if it felt a story warranted it - but so does Ipso. Both can impose big fines.
Sir Alan Moses told the FT this month that he was frustrated by the "tone" and "nasty edge" of some newspapers before the referendum, but that while he would like the Press to be more responsible, "I don't think a regulator can address it."
SubScribe raised a similar issue with Impress last month, asking if it would be able to do anything to tackle the drip-feed of negative headlines about migration that the UN and European organisations have blamed for increasing racism and hate crime. It replied that - like Ipso - stories would be considered on a case-by-case basis. As it stands, then, there would be no way of dealing with the cumulative effect of a series of stories on any subject.
Thus, the signs are that Impress is unlikely to offer any greater comfort to those who want to restrain the tabloids than Ipso.
They might hope for a "hanging judge" to oversee complaints, but referendum coverage has shown how easy it is for papers to meet "accuracy" requirements by finding a patsy MP or whoever to say the right thing to justify its approach. Free speech for columnists - even when offensive - is sacrosanct. And newspapers, unlike public broadcasters, have no obligation to provide "balanced" coverage - for if they did, how could they campaign on issues of genuine public interest?
As Moses says, it would be wonderful if our papers were less nasty and more responsible. But there is nothing to suggest that Impress would be able to achieve that. And there is no chance that any national newspaper will sign up to be regulated by an organisation linked to Mosley and Hacked Off either willingly or under duress.
So why - apart from saving face and justifying the expense of Leveson and the £2m so far handed to the recognition panel - force the issue and make martyrs of the villains who set this whole sorry ball rolling?
Weary observers of the Press might be tempted to think that if all three Murdoch papers and the Mail are united against something then it must have something going for it.
Not this time.
The Sun was wrong in its McCarthyite attack on Lineker. It was absurd to run a leader headlined "Web of deceit" complaining about "lies" on Twitter on the very day Mazher Mahmood was sent to jail for perverting the course of justice. It was crass to allow MacKenzie to crow about a victory over an "anti-free speech mafia". It was unwise to let Trevor Kavanagh continue the Lineker fight in his Monday column (when you're in a hole...) and even more so for him to heap further unwarranted insults on Fatima Manji.
The Sun exaggerates the virtues of its journalism and over-eggs the freedom of speech argument (especially when it wants to deny Lineker the right to express his personal opinion on his personal Twitter feed).
The Sun is wrong in a hundred different ways every week.
But when it comes to newspapers being regulated by an organisation appointed and overseen by a state-financed panel, it is right.
The poke at "free-speech hating celebrities, Left-leaning Hacked Off" and "odious Mosley" in its Monday leader is irrelevant. It wouldn't matter if the twelve disciples, the prophet Muhammed and Buddha were sitting in judgment. The point of principle is not who is behind any regulator that might be approved, it is the wrongness of State involvement and coercion.
And that is why Mrs May should consign Section 40 to the dustbin.