Austrian security forces carried out raids against 72 alleged Islamic extremists this week ahead of the 23th anniversary of the 9/11 attacks in the United States, citing the potential for copycat violence on the date of the plane hijackings that killed nearly 3,000 people.

The raids occurred across the European country on Tuesday, before Wednesday’s anniversary, because the 2001 tragedy remains symbolic for extremists and has inspired copycat attempts, the Directorate of State Security and Intelligence said Thursday in a statement.

Authorities thwarted an attempted attack last year on anniversary at the Vienna central station, and the risk remains high on the date around the world, it said.

Tuesday’s raids came a month after authorities foiled a plot to attack planned Taylor Swift concerts in Vienna which were then canceled. Austrian officials said the main suspect, a 19-year-old Austrian man, was inspired by the Islamic State group and sought to kill tens of thousands of fans.

The 19-year-old had allegedly uploaded to the internet an oath of allegiance to the current leader of the Islamic State group. Authorities said they also found Islamic State group and al-Qaida material at the home of a second suspect, who is 17.

The actions on Tuesday included raids on several prisons in Austria, as well as interrogations of suspects and seizures of digital devices such as cellphones to look for evidence of radical Islamic propaganda.

Franz Ruf, Austria’s director general for public security, appeared to reference the Taylor Swift plot in the statement, saying the last few weeks have shown the importance of cooperation between security agencies to counter extremism.

Interior Minister Gerhard Karner also called for stronger powers for investigators to be able to root out such plots. Currently, Austrian officials often rely on other countries — such as for the Swift concerts, where the CIA discovered the information — because unlike some foreign intelligence services, Austria can’t legally monitor text messages.

(AP)