Choosing the most vomit-inducing image from TV coverage of Tory Party conference is often difficult given the wide choice available.

The sight of Iain Duncan Smith punching the air in delight when David Cameron announced plans to reduce income tax for the highest-paid 10 per cent ranks pretty high.

But it was his comments at a fringe meeting on the supposed need for bombing raids inside Syria that proved even more chilling.

“I believe ultimately that is exactly what we will have to do,” he declared.

“There was absolute unity around the Cabinet table … that the complete package is ultimately having to deal with Isil, not Isil in one place.”

Like the Prime Minister, Duncan Smith has adopted the US style of Isil rather than the more usual reference in Britain to Isis.

“The reality, I have to be honest with you, is that it is a Labour issue … We need to carry the House of Commons on these things and so the answer here is that Labour decided that, frankly, this was not a step they wanted to take, so it conditions what we are doing,” he added.

Duncan Smith’s recognition that Ed Miliband’s refusal last year to back Cameron’s proposal to join Washington in unleashing air power against President Bashar al-Assad’s forces stopped the warmongers in their tracks speaks volumes for the peace movement role in putting pressure on Labour.

This was all the more remarkable since some new Labour hangers-on, taking their lead from their prince across the sea, Israel’s ambassador at large Tony Blair, were gung-ho for blitzing Syria.

What a difference a year makes. The siren voices backing “precision strikes” then against Syrian state forces demand the same now against Isis, which spearheads the armed struggle against Assad.

Instead of recognising that they were wrong last year to back jihadi efforts to overthrow the brutal but secular government in Syria, the US and its allies affect a “pox on both your houses” position.

There is no justification for US warplanes to bomb Syria without consent of the country’s legitimate government.

However, Damascus itself has opted to keep its head down.

Although National Reconciliation Minister Ali Haidar declared that military action “without the consent of the Syrian government would be an attack on Syria,” it has not protested to the UN and has quietly removed its forces from areas under US attack.

The government’s clear hope is that a de facto anti-Isis alliance of convenience, including Syria, Iraq, Iran and the US, will emerge to defeat the jihadi insurgency and herald future co-operation.

Assad will have drawn comfort from US Secretary of State John Kerry’s decision to use Baghdad as a conduit to forewarn his government of the timing and location of air strikes.

But such is the ongoing paranoia within the US and many of its European and Arab allies about Iranian regional influence that there is constant pressure on Barack Obama to fight a war on two fronts against both Isis and Assad.

For the warmongers, Iran is the spider at the centre of a web that includes Syria and Lebanese resistance group Hezbollah.

Michael Oren, the recently departed Israeli ambassador to Washington, encapsulated this view, claiming: “The greatest danger to Israel is by the strategic arc that extends from Tehran to Damascus to Beirut.”

Tel Aviv has expressed its preference for jihadi cut-throats over Assad by shooting down Syrian aircraft seeking to engage al-Qaida-affiliated Jabhat al-Nusra forces on the border with the Israeli-occupied Golan Heights.

More crucial to the fate of Syria has been the actions of Turkey, Saudi Arabia and Qatar.

The Saud and al-Thani family autocracies have liberally armed and bankrolled the anti-Assad jihadi groups but have been persuaded to join, in however faltering a fashion, the US-led coalition.

Turkey, with its Muslim Brotherhood-linked government headed by Recep Tayyip Erdogan, makes no secret of its determination to secure Assad’s overthrow.

Ankara has turned a blind eye to floods of foreign jihadis crossing the border into Syria and has allowed them to traffic plundered oil products in Turkey.

Yet it has obstructed Kurds from crossing into Syria to help the YPG self-defence forces retain Kobane for fear of strengthening the position of the Kurdistan Workers Party inside Turkey.

Ankara has also prevented Damascus from giving air support to the Kurds at Kobane, attacking Syrian planes.

And the decision of the Turkish parliament on Thursday to authorise troops crossing into both Iraq and Syria bodes ill for the region.

Our Foreign Secretary Philip Hammond tries to rewrite history, blaming Assad for the emergence of Isis when the fingerprints of the illegal US-led 2003 invasion of Iraq are clearly visible, to say nothing of earlier crimes against the region, such as the Sykes-Picot territorial carve-up and the Balfour declaration.

Ed Miliband concluded reasonably last year that another splurge of imperialist air power was the last thing Syria needed, but his current position is weaker after swallowing the argument for air strikes in Iraq.

Despite that, all anti-war campaigners, including within Parliament, must be on guard to ensure no mission creep in the shape of British air strikes on Syria and a slide into Blair’s dystopian preference for war without end.