Forget Syria. The Paris attacks have ignited the most vicious civil war in the UK Labour Party's history. Right-wingers in the parliamentary party (we're supposed to call them “moderates” apparently) have been seizing any opportunity to damage their leader's reputation over his reaction to the crisis.

He is a bonkers pacifist, we're told, who wants to stop our police killing terrorists when they are murdering women and children and who thinks we should try to understand IS (Islamic State) instead of bombing them. Worse, Mr Corbyn thinks we might be responsible for fuelling terrorism by our policies in the Middle East: the very idea.

He's even planning to attend the Stop the War Coalition's Christmas party. Can it get any worse? David Cameron was right in his conference speech: the Labour leader is a “threat to national security”. Lock him up, I say.

It's not just Labour MPs such as John Mann, Mike Gapes and Pat McFadden who have been attacking their leader with a disloyalty they would not have tolerated in the past from the Left of the party.

Bring back Tony Blair. He knew a thing about crusades and you'd never find him appeasing terrorists; except that it was the invasion of Baghdad that started this latest cycle of violence. Is there anyone who still disputes that the Iraq War and its chaotic aftermath are what created the seed bed in which IS incubated?

In suggesting that there might have been blow back, and that this is a reason to be wary of launching another middle eastern military adventure, Mr Corbyn is only repeating the consensus of opinion even in Western military circles. Even Mr Blair said in his CNN interview last month that there is an “element of truth” in the claim that Iraq was the primary cause of the rise of IS. There is much truth in the claim that the West has “reaped the whirlwind”. There was no IS before the Iraq war; indeed, as we now know there was no al-Qaeda, IS's predecessor, in Iraq and nor were there any weapons of mass destruction, the ostensible reason for the invasion of Baghdad in 2003. In the bloody aftermath, Iraq became a poisonous stew of sectarian conflict in which the US tacitly supported first the Shi'ite para militaries and then the Sunni militias that begat Islamic State.

Mr Corbyn is also right to say that we assisted the rise of IS in Syria in its war against the Assad regime, and that many Western allies such as Saudi Arabia have been directly financing Islamic State. Turkey helps them get the oil across the Syrian border.

Pointing this out does not justify or apologise for the terrorist attacks in Paris and that isn’t what Mr Corbyn has been saying. Understanding the circumstances in which terrorism thrives does not make any concessions to the murderers of civilians in Parisian streets. But we need to understand the mistakes of the past if only to avoid repeating them.

Another is shoot-to-kill. Mr Corbyn did not actually say that police should not use lethal force against terrorists in a situation like the Paris attacks. Of course you shoot to kill when confronting armed terrorist intent on killing civilians in cafes and rock concerts. In fact, police are trained to shoot to incapacitate, by targeting the terrorist's chest, which is generally fatal anyway.

But this is not a shoot-to-kill policy. What the Labour leader was referring to was the UK’s alleged policy of shooting IRA paramilitaries during the Irish Troubles without any attempt to arrest them. That led to episodes like Death on the Rock in the late 1980s when unarmed IRA militants were killed in Gibraltar by UK special forces.

As we now know, through revelations about the murders perpetrated by the IRA double agent Stakeknife and the activities of the Force Research Unit in British military intelligence, there were many “extra-judicial” killings in Northern Ireland. They were just called Big Boys' Rules.

After a critical investigation by the former Manchester Police Chief, John Stalker, in the 1980s into the Royal Ulster Constabulary it was made clear that police officers could not act as judge, jury and executioner. Unfortunately, this was not enough to prevent the killing of unarmed Jean Charles de Menezes in London in 2005

But to be absolutely clear: the British police do not have a shoot-to kill-policy.

Effectively, then, Mr Corbyn was simply restating the rules of engagement of British police and military personnel. Police officers are still subject to the law even when they are in an exchange of fire with terrorists. They have to justify lethal force, and this surely is the only sensible and reasonable way to conduct anti-terrorist operations in a democracy.

So why is Mr Corbyn being pilloried as a naive fool and IS's useful idiot by stating the obvious? Well, it is largely because his own parliamentary party is actively trying to misrepresent its own leader. One “moderate” shadow minister reportedly “felt physically sick” when he heard Mr Corbyn reject arbitrary shoot-to-kill and claimed he was “not fit to be our leader”. He must have a very weak stomach.

What the party's leader said in his interview with the BBC's Laura Keunssberg was: “I’m not happy with the shoot-to-kill policy in general. I think that is quite dangerous and can often be counter productive.” When he clarified this yesterday, stating that his supported “strictly necessary force” needed to protect civilians in a terrorist strike, this was widely reported as a “U-turn” a “climb-down” or “back-tracking”.

I have to question some of the reporting because these statements were not contradictory, for reasons I have explained. Of course, the reporters are only channelling the views of Labour MPs Chris Leslie and Keith Vaz who appeared to believe that Mr Corbyn rejected any killing of terrorists. But that is disingenuous. What do they want him to do? Routinely arm the police? Shoot first and ask questions later?

I keep reading columnists and politicians arguing that we shouldn't be squeamish and that civil liberties come a poor second to civilian safety. But it is never clear what they mean by these phrases, and I don't believe they have much idea themselves. Internment without trial? “Enhanced” interrogation?

They are playing to the press gallery, just like so many of Labour's current crop of MP. But this misrepresentation of Mr Corbyn's views on the origins of IS or his reservations about military intervention in Syria are not going to win any votes for Labour, from Rupert Murdoch or anyone else.

Labour MPs are putting their own war on their leader before rational debate about Western policy post-Paris. They are being driven by their own animus into wrecking their own party. It seems blindingly obvious to me that if anyone can justifiably be called a “moderate” it is the Labour leader himself.