JERUSALEM — “If in Belgium, they continue to eat chocolate and enjoy the good life with their liberalism and democracy, and do not understand that some of the Muslims there are planning terror, they will never be able to fight against them," Israel’s minister of intelligence and atomic energy, Yisrael Katz, told Israel Radio on Wednesday morning.

It might seem like harsh criticism after more than 30 people were killed Tuesday in two terrorist attacks in the Belgian capital. But if there’s one thing terrorism experts can mostly agree on, the attacks in Brussels will not be the last in Europe.

And it might be time for Europeans to get used to some of the more invasive security techniques that Israelis have been using for years.

“It took Israel years to develop a good security system, and we paid with a lot of blood before the system was created properly,” said Simon Perry, a professor at the Institute of Criminology at Hebrew University in Jerusalem. “Europe needs to invest resources in this, but also the population needs to be involved in such a process.”

Such a system, which in Israel includes looking through bags and personal belongings at the entrances to malls and other public places, as well as more than one layer of security checks at airport, is a high price to pay for any population that wants to maintain privacy. Perry said Europeans — and Americans — will be willing to submit to such invasive checks only if terrorist attacks continue.

“I don’t expect them to adopt the system we have in Israel immediately, but it would be good for Europe to have a system ready in the drawer. They will not be able to prevent the first wave of attacks but might be able to stop the second wave,” Perry said.

In Germany, Peter Neumann, a researcher who focuses on Islamist terrorism, has been particularly vocal about warning that Europe may have to accept the fact that terrorist attacks could become more common.

He told the German TV channel ZDF: "Whatever arrests will be made in the coming days, we should not assume that the threat will consequentially be over. It's a risk which will accompany us for years if not a generation. To a certain extent, we will have to get used to a constant terror threat, just like Israelis have done."

European newspaper front pages on Wednesday reflected such sentiments, implying that Tuesday's bloodshed may become part of a long chronology of attacks — with more to come. "Stay strong," Belgian daily Le Soir's headline read. The French newspaper Liberation simply wrote "Brussels. 22 March 2016."

Several factors could explain why Europe's terror threat has risen rapidly in recent months. The Islamic State's sudden rise and a slow response by European security agencies allowed thousands of homegrown radicals to travel to Syria and Iraq. Many of them have since returned — some without ever being registered, questioned or sentenced to jail.

Europe has been slow to respond, partially because of the Schengen treaty, which allows freedom of movement within much of the continent. But intelligence sharing between various agencies has also caused headaches. Even today, Europe lacks a joint database for Islamic State fighters.

Former French intelligence chief Alain Chouet told the New York Times that, among other obstacles, information was rarely passed on. "We even didn’t agree on the translations of people’s names that are in Arabic or Cyrillic, so if someone comes into Europe through Estonia or Denmark, maybe that’s not how we register them in France or Spain," Chouet said.

Apart from that, standards for European programs to counter radicalization differ dramatically: Whereas Britain's Channel program for individuals vulnerable to being radicalized is considered a model of its kind, some other large European Union member states still lack national equivalents.

Such difficulties have made it easier for terrorist groups such as the Islamic State to plan attacks with the declared goal of raising the number of Western recruits and creating societal tensions within Europe. That is why an increasing number of experts have urged Europeans to fight extremism — but to also acknowledge that not all attacks will be stopped.

"Everyone knew it would happen. And today it happened," a participant in a Brussels memorial on Place de la Bourse was quoted as saying by the TV channel RTL on Tuesday evening.

"The attacks were predictable," he said, waving a Belgian flag to commemorate the victims.

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