The Dutch authorities had already tackled this problem following a dozen serious incidents that occurred this season, shocking the country. But this time, the problem has taken on an international dimension.

Thursday night's violence erupted after the match, when hooded AZ Alkmaar fans tried to storm the area reserved for friends and families of West Ham staff. The English club had just won 1-0, ensuring its qualification for the final of the C4 after its 2-1 victory in the first leg.

West Ham manager David Moyes said he feared for his family's safety as several players broke through billboards in an attempt to end the unrest. Dutch riot police had to intervene.

UEFA is expected to open an investigation into these incidents, and further pressure will be put on the Dutch authorities to address the issue. This is a difficult task in the Netherlands as elsewhere.

"Violence in football is a multi-headed monster that is not easy to eradicate," Dutch Justice Minister Dilan Yesilgoz wrote in a letter to parliament in April.

Ajax player Davy Klaassen injured by a projectile during the clash with Feyenoord in Rotterdam, April 5, 2023 © Koen van Weel / ANP / AFP / Archives

She was reacting to the assault of Ajax Amsterdam midfielder Davy Klaassen, who was injured in the head by a lighter thrown from the stands by a Feyenoord supporter. The minister had considered that with this attack, we were "hitting rock bottom" and had ordered the opening of an investigation.

Enhanced measures

But the attack on Klaassen is far from an isolated act, which has raised questions about the reasons for this violence and how to combat it.

Also on Sunday, a referee had to interrupt a first division match between Ajax and FC Groningen when a fan entered the pitch as smoke bombs left the stands.

Dutch police called to stop the assault on West Ham fans by rivals Alkmaar, May 18, 2023 © - / ANP / AFP

In early May, more than 150 fans were arrested after chanting anti-Semitic slogans during the match between AZ Alkmaar and Ajax.

In February, a 20-year-old PSV Eindhoven fan was banned from the stadium for 40 years for attacking Sevilla's Serbian goalkeeper Marko Dmitrovic.

Several other matches involving Dutch first division teams such as FC Utrecht, FC Twente, Go Ahead Eagles, RKC Waalwijk or Sparta Rotterdam had to be cancelled due to hooliganism.

Dilan Yesilgoz, in his letter to parliament, also said the government was considering strengthening anti-hooligan measures, including banning alcohol, allocating seats in advance and harsher criminal prosecutions.

The number of stadium bans against fans last season, after stadiums reopened after the Covid pandemic, was "twice as high as in the last decade", the justice minister said.

A PSV fan attacks Sevilla goalkeeper Marko Dmitrovic on February 22, 2023 in Eindhoven © Olaf Kraak / ANP / AFP / Archives

"Anarchy"

Experts who have looked into the problem point to a number of factors, starting with the frustration accumulated by fans weaned off matches during Covid-related lockdowns.

Jan Brouwer, a law professor specialising in the study of football-related violence at the University of Groningen, noted that "football-related violence is becoming more intense".

"A lot of former fans who had had enough left, and a lot of young people arrived," he told public broadcaster NOS. "A kind of anarchy set in after banning access to stadiums (during the pandemic)."

According to the Minister of Justice, the Netherlands will turn to Great Britain to study the "English model", whose fight against hooliganism has had spectacular positive effects.

In the 1980s, English football clubs were banned from European competitions for five years after 39 people died in the European Cup of Champions Clubs final between Liverpool and Juventus at the Heysel stadium in Brussels.

Stewards intervene to contain AZ Alkmaar fans eager to attack those of West Ham, on May 18, 2023 in Alkmaar © - / ANP / AFP

The British model relies on criminal law to crack down, as well as lengthy stadium bans.

Among the hooligans punished, Klaassen's attacker was sentenced to 60 hours of community service, Dmitrovic's to two months in prison.

© 2023 AFP