“He was sentenced… under juvenile criminal law,” he told RBB TV. “And then, unfortunately, the court handed down a suspended sentence. I don’t want to pass judgement on that – that’s the independence of the judiciary – but I’m really at a loss for words.”

The opposition far-right Alternative for Germany (AfD) party described the attack as a total failure of security policy.

“If an Islamist threat known to the police was able to carry out such an act, a thorough investigation must be carried out to establish why he was still able to move about freely in the first place,” said Martin Hess, the AfD’s home affairs spokesperson.

According to Der Spiegel, Ballout told the Berlin court this spring that he had distanced himself from extremist ideology and violence.

Thomas Mücke, an extremism expert at the Violence Prevention Network VPN, told ARD television that he had met the suspect.

He said Ballout had given social workers “a very composed, very cautious, very controlled and very friendly impression”.

“And those are precisely the criteria where we realise we can’t really get to know the person,” he continued.

Some have called for Germany’s laws against terrorism to be made stricter.

Peter Neumann at King’s College London told ZDF that Germany’s criminal law on terrorism is “too lenient,” and sentences too short by European standards.

He also called for a rethink of Germany’s juvenile justice system, which he said prioritises education rather than the protection of the public.

The home affairs spokesperson for the centre-left Social Democrats (SPD), Sebastian Fiedler, told Deutschlandfunk radio that criminal law was not the problem, but the way it was applied.

“We need to look more closely at why [Ballout] still at large. Another key question is: ‘What actually happened after his release from prison? Who was he still in contact with?’ Although he was under surveillance, there was clearly a gap in the system.”

Germany’s Chancellor Friedrich Merz said it was too early to say what political consequences will be drawn from the attack, but promised there would be action: “We will have to respond with prudence, but also with determination.”

He said if individuals classified as threats could not be detained, their freedom of movement should be restricted “as much as possible.”

“I cannot understand how I can track my mobile phone from anywhere in the world… yet it is supposedly impossible, or technically unfeasible, for security authorities in Germany to determine the whereabouts of individuals classified as security threats to that same extent.”

He said he had asked the interior ministry to review the law regarding monitoring jurisdiction.