The difference between being a leader or a statesman is the ability to take necessary decisions that are unpredictable, unpopular but necessary.

David Cameron was right to lead world opinion on the invasion of Libya and right to fly in the face of opposition from his own party in pushing forward legislation to allow same sex marriage

But what about his determination to lead the civilised world in military action to show our abhorrence at the Assad regime’s wicked use of chemical weapons against innocents?

St Thomas Aquinas set out a passable rule of thumb to justify a just war.
It must occur for a good and just purpose.
It must be waged by a legitimate authority.
And peace must be a central motive even in the midst of violence.

It is right and proper that Parliament has been recalled to debate and vote on our options. But Cameron must avoid a free vote for his party. If it is government policy that we embark on surgical strikes on Assad’s military installations then there should be a three line whip as it is not a matter of conscience.

The trouble is that Labour thinking is disfigured by the Iraq war and can only be seen through the prism of the so called dodgy dossier. The default position of that old snake oil salesman Douglas Alexander is to wait for the weapons experts to report their evidence to the UN Security Council.

This is dangerous nonsense.

The Assad regime has done everything possible to hinder the collection of evidence. A five day wait. The heavy bombardment of sites destroying most traces of any evidence that can implicate the regime.

And as for the Security Council? There will be never be unanimity so long as the Russians and the Chinese dishonestly and obstinately stick to their line of never interfere with the internal workings of a sovereign state.

In some ways I can sympathise with this. But since 2005 there is scope to intervene outside the scope of the Security Council in matters of genocide. And no sentient being can fly in the face of the actuality.

Does it really stand up that rebel forces have either the capacity or the desire to use chemical weapons to murder their innocent women and children or even, as it has been suggested by George Galloway, that the state of Israel bears responsibility?

Of course not.

It would be a disgraceful cop out if we adopted the line in the nineteen thirties after the Nazis invaded Czechoslovakia that Syria is a far a way place that is not our concern.

The wringing of hands at the wickedness of the Assad regime is not enough. A clear military expression of the horror of the civilised world at the use of chemical weapons against innocents must serve as a warning to those other regimes who believe that they too can get away with it with impunity.

But we have to accept our limitations.

There can be no ground troops. There can be no attempt at air superiority and there can be no arming of the rebels.

We can’t arm the rebels simply because there is no coherent command structure. There are a lot of men with guns. Some are on the side of the angels others are gangsters and terrorists.

And there can be no attempt regime change simply because it won’t work.

Assad’s regime did what it did because it thought and still thinks that they can and will get away with it. We must prove them wrong.

We would be failing in our duty and we would be cast into a moral vacuum if we do not support a multilateral surgical strike on key military installations.

But that is as far as we can go.

Tomorrow the House of Commons has the opportunity to show courage, fortitude and determination rather than vacillation and party manoeuvring.

David Cameron has shown leadership and courage. But does Ed Miliband have the stomach to take on his left wing and union leaders to do what he must know is the right thing?

Of course a one off strike will lead to uncertainty and will rattle the cages of those who have been fighting an Islamic war for over eight hundred years.
But if we want to show that the civilised world has traded its moral compass for influence in this troubled region then we are not much better than the men of terror.

The Aquinas criteria have been met. And it is time for the civilised world to show its moral authority.

Syria is a rogue and failing state. We must now make it a pariah state so long as Assad and his gangsters are in charge.