Editor’s Note: CNN’s International Diplomatic Editor Nic Robertson is in Brussels covering the aftermath of this week’s attacks. The views expressed here are his own.

Story highlights

More young Belgians are going to join ISIS in Iraq and Syria than any other European country

There needs to be "a renewed effort to stop ISIS's free hand on our streets," says Robertson

Focus should be on international intelligence sharing and understanding communities from which ISIS recruits

CNN  — 

What to do about ISIS? Fight them for sure. Following the Paris attacks, I was flooded with anger.

And now, after the Brussels atrocities and hearing the haunting screams of children in the dark after the train attack, and in their whimpering in clouding dust at the airport, I am no less angry. But somehow I’m calmer.

The dam has broken, I can see more clearly now.

In northern European classrooms there is an oft told fable of the Dutch boy who saved the country from flooding sticking his finger in the dyke holding the floodwaters back.

As once Holland fought tides and rain, today Belgium has been trying to hold back another force of nature: A disaffected, disassociated youth, warped and wrapped in ISIS’s corrosive ideology. Their numbers have been too great for Belgian counter terrorism efforts to cope.

Recruitment center 

Per capita, more young Belgian men are going to join ISIS in Iraq and Syria than any other European country. Belgian officials say as many as 300 have left the country and about half have returned.

Belgium: Europe’s front line in the war on terror

We could feel an attack coming, indeed I suggested as much last week, and so did the Belgians.

Their fingers have been in every hole of an increasingly leaky security dyke. Saleh Abdeslam’s arrest last week punched a new breach, one they couldn’t plug.

Whether revenge, or racing to beat arrest following Abdeslam’s lawyer saying he was helping police with their inquiries, the cell that attacked Tuesday clearly figured that now was the time.

It feels like the dam is breached and with it comes a clarity of what to do next.

New effort to beat ISIS 

It’s time for an holistic overhaul. An end of talk and a time for action. A renewed effort to stop ISIS’s free hand on our streets by improving international intelligence-sharing and understand the communities ISIS recruits from.

One of the most successful “deradicalizers,” the UK, is going broke while the government figures out a comprehensive strategy to stop jihadi wannabes joining ISIS’s ranks. And intelligence-sharing across Europe’s borders is often discussed but rarely breaks new ground. No one expects the results to be fast, but we the people do expect concrete action from our politicians.

Mapping ISIS attacks around the world 

As in sport, every gain from every incremental adjustment of training, tactics and preparation has become a formula to success.

It’s time for an acceptance that there’s no silver bullet to beating ISIS on our streets. Improvements at every level are needed and they need to start today.

I’m quite sure my old school class mate Andrew Parker, who now heads British intelligence service MI5, and his teams know this too. But it’s easier said than done. Breaking down old habits to allow easy speedy and transparent intelligence-sharing across international borders will need to overcome centuries of mistrust.

I know I speak from the periphery and don’t have to balance national interests versus international obligations, but ISIS is tipping the scale.

We have a common enemy, they attack us like we are one and exploit our individuality.

As the Belgians and French know from the Brussels and Paris attacks, ISIS is not al Qaeda. The networks nurtured in ISIS training camps are more robust, more spy savvy, more tech savvy, harder to crack than their parent’s generation of al Qaeda jihadist.

Same rhetoric

President Barack Obama, speaking half a world away in Cuba, said what we have heard so many times. “This is yet another reminder that the world must unite.”

President Francois Hollande speaking after meeting his defense council said “we need unity at a European level.”

And after consulting with his “COBR” emergency cabinet committee, British Prime Minister David Cameron proclaimed that “these were attacks in Belgium but they could have well been attacks in Britain or in France or in Germany.”

The rhetoric is strong and there is no reason to doubt it is not well intentioned.

But Obama continued his long standing trip to Argentina, while Cameron went back to averting a potential crisis in his cabinet and trying to head off a Brexit vote – the latter brought on in part by ISIS. It feels like business as usual.

We’ve been hearing about the need to unite and cooperate intelligence agencies for more than a decade – since before the Madrid train attacks in 2004.

So who’s going to lead this unifying effort against ISIS? When are they going to do it?

The dyke is breached and our feet are wet. What are we waiting for?

#prayforbrussels: World mourns with cartoons and open doors