Followers of the thought of Waleed Aly no doubt will regard this week’s homicide-suicide attacks in Brussels as another manifestation of what he has termed a “perpetual irritant”. This is how the Monash University academic and Fairfax Media columnist responded to news of the 2013 Boston Marathon bombings.

At the time, Aly suspected (wrongly as it turned out) that the “perpetrators” of the attacks that closed down Boston for some days were right-wing, “self-styled American patriots”. In fact, the terrorists were militant Islamists Dzhokhar and Tamerlan Tsarnaev. They immigrated to the US, having been born in Kyrgyzstan to a Chechen family.

Aly, who now has programs on ABC Radio and the Ten Network, used the occasion of the Boston attacks to lecture at large about terrorism. He described terrorism as “a grotesque form of theatre” and added that “while it is tragic and emotionally lacerating, it kills relatively few people and it is not any kind of existential threat”.

With such views it is no surprise that Aly has become something of a media star of the Left in Australia, highlighted by his role as a presenter of The Project. Yet the reality is that terrorism has become an existential threat to the survival of Western Europe as we have come to know it.

Belgium is a multicultural nation that has allowed immigrants to settle and enjoy its democratic freedoms, access to health and education services and welfare safety net. Yet some first, second and even third-generation Belgian citizens or residents of Muslim background regard the Belgian state as an enemy and wish it replaced by an Islamic caliphate.

Of course, the overwhelming majority of Belgium’s Muslims are law-abiding citizens. Yet there are enough Islamists to wage terrorist attacks within their own nation and in France (as the attacks in Paris last November demonstrated). This amounts to an existential threat to both nations. Other European nations also are threatened, albeit to a lesser extent at the moment.

It so happens that the Belgians have been the most tolerant of all Europeans to the operations of Islamist extremists and to the preachings of radical mullahs in mosques and prayer halls. Belgium’s reward for its acceptance of such diversity became evident with the attacks on Brussels’ airport and railway system this week.

It is understandable that democratic politicians want to avoid facing up to the threat to their societies, which has become a reality since 1999 when Jordanian-born Abu Musab al-Zarqawi set up what became the so-called Islamic State or Daesh — some years before the invasion of Iraq by the coalition of the willing comprising the US, Britain, Australia and Poland.

Malcolm Turnbull was correct this week in identifying Western Europe’s security weaknesses — with particular reference to its inadequate border control — as a factor in the Brussels attacks. However, he underestimated the significance of the threat by referring to the attackers as cowards.

To engage in an act of homicide-suicide is one of the worst crimes — especially in view of the indiscriminate targets involved. But it is not the act of a coward. Most terrorists who engage in such activity are courageous individuals who are willing to die in support of their cause. This makes them all the more dangerous than if they did not remain present at the scene of the crime.

In recent years there have been several apparent lone-wolf Islamist attacks on the US. Even so, President Barack Obama refuses even to use the word Islamist. This despite the fact the Islamists who have attacked the country in which they were born or in which they have settled have not denied their religious and ideological motivations.

In Britain, however, Prime Minister David Cameron has referred to “Islamist extremism”. In Australia, the Prime Minister has adopted a softer tone on this issue than his predecessor, Tony Abbott. Yet in his address to the Sydney Institute last July, Turnbull did refer to an entity he described as “the Islamic terrorist” and acknowledged that Daesh abided by what he termed “a twisted and archaic interpretation of Islam”.

Interviewed by the AM program on Wednesday, Attorney-General George Brandis reminded listeners that “we have had three individual terrorist events in Australia since September 2014”, each of which “has been in the nature of a lone-wolf attack”. He added that “during the same period we have disrupted six other imminent terrorist events”.

Brandis’s comments point to the crucial work being done by ASIO, the Australian Federal Police, and state and territory police forces.

The best way to tackle the problem of terrorism, irrespective of its source, is to be honest about the problem. The Belgians erred by going into denial about the real threat to their society from Islamist terrorism.

Obviously, Australia does not have as much to fear from the threat as the nations of Western Europe or Muslim-majority nations such as Iraq. Even so, the threat in Australia is much more than an irritant — perpetual or otherwise.