While the world’s attention was focused on events in Paris in recent days, an even bloodier atrocity was taking place in Nigeria. Boko Haram, an extremist Islamist organization, was adding to its long record of barbarism. After leaving an estimated 2,000 people dead in a clash near the town of Baga, Boko Haram strapped a bomb to a 10-year-old girl and sent her into a busy Saturday market. The explosion killed 20.

Boko Haram may not have a formal link to the terrorists who struck in France. Nor may it share any recognizable philosophy other than the indiscriminate use of violence to achieve its ends. “Boko Haram” can be translated as “western education is a sin.” Its mandate, then, is murder and mayhem aimed at halting any movement towards democracy, tolerance or individual rights. As with other Islamist groups, however, it bases its acts on its own warped interpretation of Islam. Whatever the French terrorists were hoping to achieve by killing 17 people, they too justified it via their devotion to an Islamist code as they perceived it.

It is this very lack of coherence that makes the upsurge in Islamist violence such a global threat, even as it is used by some to minimize the nature of the danger. However informal, ill-organized or lacking in specific ties, Islamist extremism is a scourge unconstrained by geography.

An Al-Qaeda group in Yemen claimed responsibility for the attack on Charlie Hebdo as “revenge for the honour” of the Prophet Muhammad, although at least one attacker proclaimed allegiance to the self-declared Islamic State, or ISIS. Some analysts maintain the attacks were a bid by Al-Qaeda to reclaim the public spotlight from ISIS, after a year in which ISIS gained significant ground in Syria and Iraq.

Both are separate again from Al-Shabaab, an Islamist terror group based in Somalia responsible for a massacre at a Kenyan mall in which 67 people were killed. Libya, meanwhile, is torn between an array of Islamist militias battling for control against non-Islamist powers. UN-backed peace talks intended to take place in Libya last week were moved to Geneva due to the danger. Even within Al-Qaeda, different factions in different regions lay claim to the name.

This may not represent a “clash of civilizations” as some would have it. Islam does not advocate violence, and those claiming to kill for Allah are perverting a religion that wants no part of them. But Islamist extremism acts as a handy banner for any embittered group or individual seeking a justification for violence, and it has been shown to exert a dismaying lure across national borders, from the civil wars of varying intensity now being waged in Yemen, Afghanistan and Pakistan, to the insurrection in the Chechnya region of Russia — subdued in a brutal five-day war in 2008 but still a hot spot of Islamist anger — to China’s efforts to put down its restive Uighur population in Xinjiang province, to Egypt, where both ISIS and Al-Qaeda have claimed responsibility for recent attacks on pipelines running to Israel and Jordan. And, of course, to the Islamist or Islamist-inspired terrorist attacks now mushrooming across the developed world.

It is the global nature of the threat that has put Islamist extremism at the top of the international agenda. More than 40 world leaders are in Paris this week for anti-terror talks. U.S. President Barack Obama will host another gathering next month, which Prime Minister Stephen Harper’s office says he will “definitely” attend.

There is always a danger, in confronting outrages like that in Paris, of overreacting in the face of public alarm, without a full understanding of the extent of the actual danger. But in the 13 years since the 9/11 attacks, Islamist extremism has shown itself to be an insidious force that will not wither without fierce opposition. It feeds on inchoate feelings of anger or bitterness, of whatever origin, its only goal being to ruthlessly exploit that disaffection in pursuit of bloodshed. It cannot be defeated only by sending troops or warplanes against its forces — though that will sometimes be necessary — but it also thrives on being ignored or explained away as an expression of understandable dissent at recognized injustices. It is crucial that countries such as Canada join others in seeking solutions to weaken and defeat it, whether through education, joint action or international counter-terrorism activities.

Mr. Harper is right to join others in seeking remedies. This is not an issue to be exploited for political purposes, on either side of the partisan divide. It is a fundamental problem of the modern world, and needs to be fought on all fronts.