The prospect of lone jihadists perpetrating regular terror attacks in the West — once merely the stuff of nightmare — is becoming all too real. After three recent attacks in North America (two in Canada and one in New York City) by radicalized converts to Islam, it has become clear that the equation has changed: This new wave of one-man attacks is emerging as the most immediate and serious terror threat to Western population centres.

The likelihood of home-grown attacks appears to have risen by an order of magnitude since Western powers began their air campaign against ISIS in Iraq and Syria in August. The group’s spokesman declared on September 21: “If you can kill a disbelieving American or European or an Australian, or a Canadian, then rely upon Allah, and kill him in any manner or way however it may be. Do not ask for anyone’s advice and do not seek anyone’s verdict. Kill the disbeliever whether he is civilian or military, for they have the same ruling.”

So far, soldiers have been among the main targets of jihadists — from the murder of three soldiers by Mohamed Merah in France in 2012, to Lee Rigby in London in 2013, and now several more in North America.

Lone jihadists now can decide not to go through the ordeal of travelling to the Middle East to assist ISIS. Instead, they can do it in their own neighbourhood. While most of the focus among law enforcement has been on jihadists returning from foreign battlefields, they now have an entirely different threat to watch for.

Having missed the warning signs, Western governments are playing catch up. As early as 2007, the emergence of the lone jihadist, loosely linked to al-Qaeda but not formally trained or inducted by Osama bin Laden’s lieutenants, was keeping law enforcement awake at night. One of them was arrested in May of that year in Nancy, France: he was planning attacks against the U.S. Consulate in Luxemburg and a Mc Donald’s restaurant.

Bernard Squarcini, then the head of the French domestic security services, stated that “An ideological transformation can be done in three months on the web. An individual can at night auto-radicalize himself via the [internet] and get in touch with leaders of terrorist organizations.” France’s then Interior minister, Michèle Alliot-Marie, said that the use of the Web by terrorists was “one of my major concerns, and one of the priorities assigned to the [security] services. This requires additional material; forces specialized in fighting cyber-criminality, legal resources. I want us to be able to stop the terrorist propaganda, find the operational networks, track them down and prevent them from acting.”

That was then. In 2014, the explosion of the use of social media warrants even more tools and resources to counter radicalization.

Western security services are overwhelmed with workload on counterterrorism: from returning jihadists to the homegrown threat to established terror cells. Just one statistic summarizes the enormity of the task at hand: To properly track and follow a single jihadist, you need work from about 30 officers. The overstretching and pressure on the security services helps explain why even among the most experienced officers, the French for instance, there recently have been blunders.

In light of this, how can one comprehend why the UK Foreign and Commonwealth Office Counter Terrorism Unit’s budget will be reduced, and staff cut from 85 to 50? Western law enforcement agencies need and deserve a large increase in terms of both manpower and budget.

As Christophe Chaboud, the ex-French counterterrorism czar, put it in 2008: “An isolated individual can today inflict as much damage as an organization.” Imagine the following scenario: A suicide bomber blows himself up in a department store in Paris, another one in a club in London, another one in a restaurant in Rome. These individuals may have no links, and not be part of any cell. But they can paralyze cities of millions. How do you find them and prevent them from acting?

It is beyond difficult to track down radicalized individuals who fly totally under the radar. But in almost all cases, we typically find that there were clues that might have aroused suspicion. Using those clues to prevent tragedy is a huge undertaking indeed.