Every member of the Canadian Parliament, or any Canadian citizen, who is interested in the fight against the Islamic State should watch, read or listen to Hilary Benn's speech in the British House of Commons this week.

Mr. Benn is the Labour Party's shadow foreign secretary. His party is riven by how to combat the Islamic State, and his speech brilliantly explained why Britain should change its policy and begin to deliver air strikes against IS in Syria.

The United Nations Security Council has called on countries to "take all necessary measures" to combat IS and eradicate the group's haven, he said. Moreover, he said, "the question which confronts us in a very, very complex conflict is at its heart very simple. What should we do with others to confront this threat to our citizens, our nation, other nations and the people who suffer under the yoke, the cruel yoke, of Daesh [another name for IS]?"

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After 10 hours of debate, the Conservative majority and many Labour MPs, such as Mr. Benn, voted 397 to 223 to authorize air strikes against the Islamic State and Syria, reversing a 285-272 vote in August, 2013, not to join the air campaign.

After the Islamic State-inspired massacres in Paris and Beirut, and the downing of a Russian plane with 224 fatalities, countries other than Canada are beefing up their military engagement against IS.

France has already committed to doing more, and the French government is urging others to follow suit. In response, the German cabinet agreed to deploy six reconnaissance jets (not fighter jets), 1,200 soldiers, a refuelling aircraft and a frigate to the IS fight, plus 650 soldiers to Mali to assist the French there. (Italy is preoccupied with the chaos in Libya.)

The United States announced that it would send an additional 100 to 150 special operations troops to join those already deployed in the Iraqi theatre – far short, it must be said, of deploying significant numbers of ground forces.

Nonetheless, France, Britain, Germany and the United States are upping their front-line commitments at the very least to halt the Islamic State's territorial expansion.

The Canadian government, by contrast, proposes to withdraw from the front lines. The country's fighter jets will be removed from the fray, and Canada instead will participate far from the front lines by training Kurdish fighters.

Geographically and metaphorically speaking, Canada will not be "back" as a more active international participant, as the government boasts, but will be moving backward, away from the coal face of the fight against IS. Allies will be moving one way; Canada in another.

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Canada's active military contribution was small, but it was nonetheless present, testament to a commitment and solidarity. Now, that will be diluted. We can just imagine how our allies will view this Canadian decision. They will say all the right things in public, but remember the Canadian decision privately quite differently.

There is understandable confusion that tangles up memories of the disastrous U.S. invasion of Iraq and the combat against IS.

Iraq under Saddam Hussein was a thoroughly odious regime, but it posed no threat to any country, having been expelled from Kuwait. Iraq could easily have been contained without an invasion.

The Islamic State is different. It proposes to establish a caliphate that does not recognize boundaries. In other words, it wishes to destabilize a region. Moreover, it has attracted fighters from many countries to the cause. It has indoctrinated them in jihadi theory and practice within IS territory and beyond, with a mission both to spread the caliphate's territory and to kill apostates (Westerners, Shia Muslims and other non-Sunni Muslims).

Islamic State believers have an apocalyptic vision of a great battle between Muslims such as themselves and infidels, a vision that emboldens IS to commit unspeakable atrocities against women and all those who do not partake of their vision. Read the recent books about IS and the superb article in the March issue of The Atlantic by Graeme Wood to understand the true nature of the threat.

Air strikes alone can damage but not defeat the Islamic State. It will take some sort of peace arrangement within Syria (and one is not at hand although negotiations continue), plus ground forces eventually. In the meantime, air strikes are the best that IS foes can do, along with training and humanitarian assistance.

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That is what Canada's closest allies believe. The Canadian government thinks otherwise.