Media playback is unsupported on your device Media caption White House Press Secretary Sarah Sanders explains why Mr Trump rounded on his former adviser Steve Bannon

It's not unusual for former political allies to fall out. It happens all the time. But normally it's done in private, and maybe hinted at in public. Not this time. Not with this President.

This is a vicious knife fight between Donald Trump and his former campaign chief and White House Chief strategist being played out across social media.

Other Trump family members and supporters are piling in too. Why? Because Steve Bannon has enraged Donald Trump with his description of a meeting that took place between the president's son, Don Jr, and son in law, Jared Kushner, with a Kremlin-linked, Russian lawyer as unpatriotic and treasonous.

He's talked about how clear it is what the Special Counsel, Robert Mueller, is investigating - whether the Trump organisation was laundering dirty Russian money. Donald Trump has fired back in the way only he knows how. He has met fire with fire, accusing Bannon of having lost his mind, of not being that influential, of being a pretender. Lost his mind. Wow.

So much for the spat. Does it matter? Well yes it does.

Image copyright Reuters Image caption Mr Mueller's team is investigating whether the Trump campaign colluded with Russia during the election

To anyone who will listen, Trump and his supporters have insisted vociferously, angrily, indignantly that there is no evidence there was collusion. In one recent interview with the New York Times conducted over the New Year at Mar-a-Lago, Trump raised the subject again and again and again, denying collusion 16 times.

Bannon's comments won't alter the course of the Mueller investigation - his team is quietly getting on with its investigation and following where the evidence takes them - remember there have already been three people charged in connection with this. But it matters in the war of words on social media.

The narrative of Trump fidelis is that this is a 'nothingburger', or to change my food metaphor, sour grapes from the Democrats after their shock election defeat.

Some ideological outriders have been saying that what the president should do is fire the special counsel, and bring his existentially threatening investigation to an end. But how much more difficult is that propaganda battle now to wage, when one of the principal actors from the Trump campaign, and the first six months of the Trump presidency talks openly and on the record about treasonous and unpatriotic behaviour.

Image copyright Getty Images Image caption President Trump boards Air Force One with his then top aide, Steve Bannon

The firing of Bannon last August the president did with a heavy heart. But it seems that hell hath no fury like a Bannon scorned. Or as President Johnson noted when dealing with the troublesome J Edgar Hoover in the 1960s - better to have him inside the tent pissing out than outside pissing in. Bannon is outside, and taking careful aim.

But if the Bannon accusations are damaging (and they are), there is one aspect of this which will be causing quiet delight in the White House. If you cast your mind back to the summer, the appointment of General John Kelly (and the firing of Bannon) was meant to mark the moment when discipline was imposed on an unruly, freewheeling, chaotic administration.

There would be a chain of command. Order. Discipline. Systems. Well Steve Bannon was gone, true; but he was still an important voice in the president's ear. Remember this iron law of governing. It doesn't matter what a person's job title is, it is what proximity they have to the centre of power. Bannon was on the outside, but he was still a source of counsel. Now he is not just on the outside, he is in outer darkness.

Media playback is unsupported on your device Media caption Steve Bannon's three goals for the Trump presidency

So what is Steve Bannon's next move? Well I make one confident prediction: it won't be to roll up his tent, pack his knapsack and skulk away with his head drooping. Bannon is campaigning to tear down the Republican establishment, and in Breitbart News he has a fairly formidable weapon with which to wage his war. Bannon wants candidates in this year's mid term election who will threaten the existing Republican leadership, who will follow the populist, nationalist policies that led Donald Trump to election victory in 2016. You have two men now violently fighting it out for the hearts and minds of the Americans who propelled Donald Trump to victory.

When I came to work this morning I thought nothing would or could eclipse Donald Trump's tweet about Kim Jong-un. But now it seems that Mr Bannon and President Trump are locked in a battle over who's got the bigger button and whose is most powerful.

Next move, Steve Bannon. And this is so much less life-threatening than real nuclear war.