Today’s vote in the House of Commons on British military intervention in Iraq is likely to negate the good work done by MPs in August last year.

On that occasion, they defeated Prime Minister David Cameron’s attempt to drag Britain into a war against President Bashar al-Assad in Syria behind the US.

Such a military escapade then would have been a disaster had it led to the downfall of the secular regime in Damascus.

By now, the Islamic State (Isis) would rule across most of Syria and not just parts of the east and swathes of northern Iraq.

Non-Sunni Muslims, Christians, Kurds and other religious and ethnic groups would be fleeing or dying in even bigger numbers than they are at the hands of Isis now.

Today’s vote could have the same unintended consequences because US ruling circles have not fundamentally changed their agenda in the Middle East.

They want compliant regimes across the region that will allow US big business full access to natural resources and transport routes, backed up where necessary by US or Nato military facilities.

All opposition to key US ally Israel is to be neutralised where it cannot be eliminated.

In pursuit of this long-standing strategy, prolific lip service is paid to notions of freedom, democracy, rights for the Palestinians and fighting a war on terror.

But MPs should not be fooled about the real motives of those forces which shape President Barack Obama’s foreign policy.

These corporate and military chiefs have already ruined his reputation as a peacemaker, turning the Nobel peace prize-winner into the commandant of Guantanamo Bay and the chief marshal of killer drones in Pakistan and elsewhere.

Indeed, US duplicity in Syria has already been signalled by the decision to fund the so-called “moderate” anti-Assad opposition, including the defeated and largely defunct Free Syrian Army, and to bomb Isis-controlled oil refineries.

It will take months to resurrect a new FSA and, unless the real purpose is to weaken the economic as well as military position of the Assad government, oil installations should be liberated not destroyed.

Joining US military action in Iraq will almost inevitably suck British armed forces into the wider conflict against Isis and, by extension, into US subversion of one of the region’s few secular administrations in Syria.

It will be not so much a case of “mission creep” as mission gallop.

What’s needed instead is support for those anti-Isis forces in the region which are genuinely broad-based and secular.

The Syrian, Iraqi and Kurdish authorities on the ground should set the terms for assistance in that struggle, endorsed by the United Nations, not the US president, his wire-pullers and their imagined allies in Turkey and the Gulf states.

This should not include the very Western military intervention which helped breed Isis and similar fundamentalist groups in the first place.

Today’s vote will reveal whether Ed Miliband and the Labour Party leadership really have learned the primary lesson from recent calamitous British and Western escapades in Iraq, Afghanistan and Libya.

Britain’s trade unions indicated at the TUC earlier this year that they have. Prime Minister Cameron clearly has not.