In his Holocaust memoir, Night, the late Nobel laureate Elie Wiesel hauntingly described the challenges of hanging the young and starving:

It's roll call at the Monowitz concentration camp, and three prisoners are executed. Among them is a boy too light to die quickly when the chair beneath him is kicked over. He is still writhing when Wiesel and the other prisoners are marched past. One prisoner looks at the boy and asks, where is God? Wiesel replies that God is in front of them, hanging from the gallows.

Hangings at Saydnaya prison

The guards at Syria's Saydnaya prison — a military prison near Damascus — lack the Nazis' patience. According to an Amnesty International report released this week, as many as 13,000 prisoners, mostly civilian opponents of Syrian president Bashar al-Assad, were killed at Saydnaya between 2011 and 2015. (Naturally, Syria has rejected the report.) Like the boy at Monowitz, some were too light to die easily by hanging. Guards would pull down on their feet to break their necks.

There are other prisons in Syria and thousands of other victims. For many, we have photographic evidence. If this is not a genocide, it is nevertheless slaughter on an industrial scale. It is the sort of mass atrocity that world leaders pledge every year — as they did only two weeks ago on the anniversary of the liberation of Auschwitz — to prevent from ever happening ever again. And yet here we are, watching it happen again and doing nothing to stop it.

As of the time of writing, neither Prime Minister Justin Trudeau nor Foreign Minister Chrystia Freeland had issued a statement about the latest Saydnaya revelations. And why would they? The whole thing has become rather embarrassing.

For six years now, Assad has been hanging, gassing, torturing and barrel bombing Syrians to death. He's been aided in this task by the governments of Iran and Russia, with which Trudeau has pledged to mend relations.

In October, then Foreign Minister Stephane Dion promised Canada would hold both Russia and Syria to account, vowing that, "The path of dangerous belligerence will not succeed." This is what's known in the parlance of our times as an "alternative fact." Clearly, Assad's belligerence — if that term can be applied to mass murder — is succeeding. It's succeeding because the world, Canada included, is standing aside as Assad perpetuates an ongoing crime against humanity.

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Trudeau has never suffered from limited ambition about what Canada can accomplish under his leadership. (Brendan McDermid/Reuters)

To be sure, Canada's ability to shape events in Syria is limited. But Trudeau has never suffered from limited ambition about what Canada can accomplish under his leadership. "Canada is back, my friends," Trudeau said at the Paris climate conference in 2015. "We're here to help."

He sounded ridiculously self-important at the time. But now, with right-wing populism sweeping Europe, Britain engrossed in a bout of pathological Brexit masochism and a grubby zealot debasing the White House for the next four years, Canada — led by an unabashed champion of liberal pluralism — does appear exceptional. The headline on a recent New York Times column declared that Canada is leading the free world.

So, lead.

But recognize first where in the world leadership is most needed, where resources should be invested and political and diplomatic capital should be spent. It's not peacekeeping in Africa. It's not acceding to the Arms Trade Treaty. It's not even climate change. It's Syria.

Assad is not a partner

Assad's murderous rule is an affront to every value for which Canada claims to stand. It's the main source of a refugee crisis that has destabilized much of the globe and acted as a tailwind for nativist politics in several Western democracies. And it's the cause of far too much death.

When Trudeau meets with President Donald Trump next week, a top priority should be persuading the American leader that Assad is not a viable partner in the fight against ISIS, as Trump appears to believe, but a war criminal who must be brought to justice.

As Trudeau seeks to re-engage with Iran, he should simultaneously loudly condemn the country for aiding and enabling Assad's extermination of his own people.

And Canada should consider the advice of McGill international law professor Payam Akhavan, who for months has been urging Ottawa to bring a case against the Syrian government to the United Nations' International Court of Justice for its failure to punish individuals responsible for crimes against humanity inside the country.  

When asked to explain inaction in the face of genocide and other mass atrocity crimes, among the most common excuses is: "We didn't know." It's a shabby plea. We won't be able to make it about Syria.

This column is part of CBC's Opinion section. For more information about this section, please read this editor's blog and our FAQ.