Again an attack. Again on German soil. Again the attacker was known to police. Again a terrorist—not holding the steering wheel of a truck but rather a shoplifted knife. Again the question: How can it be prevented?

Once again blood was spilled on German soil by a terrorist, this time in the city of Hamburg. July 28 was an ordinary day for customers in the local supermarket Edeka, until Ahmad Alhaw grabbed a knife from the shelf and attempted to murder as many people as he could. One died and multiple others were injured until a few brave people stopped the attacker.

Alhaw now sits in custody while the media and politicians speculate about his motives. The word “terror” was carefully avoided at first: He had apparently acted on his own and had no obvious connections to any terror networks. Everything points to “Islamic motives,” though his psychological liability is still being questioned. While politicians and media argue about the politically correct way to phrase his motive, Alhaw bluntly calls himself a terrorist.

Germans are worried: How could this have happened again? And when will it happen next? Alhaw was on the radar of German security agencies. He was meant to be deported. Yet he stayed—and killed. He was known as Islamist, but he was not considered to be a dangerous jihadist. That suddenly changed, according to the security agencies. Bild reported on July 30 (Trumpet translation throughout):

Those who knew the perpetrator also seem to confirm the version of the man’s sudden mind change toward being an Islamist. A 33-year-old neighbor of the Palestinian says he used to drink a lot of alcohol, smoked hashish, and consumed cocaine. A while ago, he was still frequently playing soccer with other residents—he hardly did all of that any longer. Instead, he barely left his room. He was “crazy” and often screamed “Allahu Akbar” across the hall, roommates recount. Unsolicited, he also loudly recited lines from the Koran in refugee cafés.

How can Germans prevent an Islamist man from becoming a dangerous jihadist, and then picking a knife up off of a shelf and suddenly stabbing people? The Edeka supermarket in Hamburg removed its stock of knives from its shelves in order to at least feel a little bit safer. But obviously that is not the solution.

The fear in Germany is growing. What will it lead to?

Alhaw arrived in Germany in 2015 as a refugee. He was denied asylum but hadn’t been removed from the country. His attack puts the focus back on radical Islam and on the refugee crisis just a couple of months before the next German election.

It also reminds Germans of the Berlin truck attack on Dec. 19, 2016, which was also committed by a refugee who was supposed to have been deported. Trumpet contributing editor Brad Macdonald wrote at the time:

There was no dramatic and forceful response from [German Chancellor Angela] Merkel or her government. No meaningful change in direction. No recognition that her migrant policies are flawed and have clearly put Germany in danger. There were plenty of platitudes, but no major decisions; plenty of promises, but no noticeable actions.

The reaction to this supermarket attack has been the same. Mr. Macdonald continued:

It is very human amid such a crisis to seek vengeance, and to go into self-preservation mode. The Berlin attack will add massively to the public’s frustration and disillusionment with mainstream politicians, particularly Chancellor Merkel. In fact, many Germans consider Merkel responsible for these attacks.

These frustrated Germans don’t want to persecute migrants, beat them up, imprison them or kill them. They are not Nazis seeking to commit genocide against German Muslims. Most are regular, sound-thinking, rational people, many of whom have great sympathy for the migrants. But they are justifiably concerned and alarmed at the impact millions of migrants are having on Germany—on its institutions, its infrastructure, its economy, its culture and its people. They are frightened by the prospect of more terrorist attacks. And they are concerned that Merkel’s government refuses to give serious attention to their fears and worries.

Merkel’s failure to react more energetically to the Berlin attack, her failure to recognize the extent of the problem and the part her policies played in creating it, and her failure to take the German public’s concerns seriously are deeply alarming. By failing to tackle these issues, Angela Merkel is turning the German people into a ticking time bomb!

The more disillusioned, frustrated and angry the German people become, the more vulnerable they will be to radical politics and radical leaders with radical solutions.

Each terrorist attack adds to that vulnerability. “Germany needs someone stronger, someone more confrontational, someone more decisive, and someone capable of making hard and unpopular decisions,” Mr. Macdonald concluded. “Watch for that man to rise.”

These terrorist attacks are building to a massive transformation in German politics. For more on where this transformation will lead, read Mr. Macdonald’s article “Was This Germany’s 9/11?”