Tensions are high in Europe as anger over the Israel-Hamas war has led to a rise in bomb threats and growing fears of hate crimes.

In Germany's capital, Berlin, police reported four cases of the Star of David being daubed on the doors of Jewish residents — echoing the Nazi wartime practice of painting the star on Jewish businesses to discourage people from frequenting them.

In London, the Met Police said they have seen a rise in antisemitic and Islamophobic crimes reported since Hamas militants attacked Israeli soldiers and civilians on Oct. 7. Three Jewish schools in the British capital closed amid fears they might be targeted.

In France, which has Europe's highest Jewish and Muslim populations, there has also been a rise in security threats. 

France's Justice Minister, Eric Dupond-Moretti, announced Friday that 22 judicial enquiries had been opened following an increase in false bomb threats in recent days. He said many of the threats were made by "kids" who didn't understand how serious their actions were.

At least 11 French airports were evacuated Thursday following bomb scares. Some were cleared for brief periods, but Transport Minister Clément Beaune pointed out that it led to flight scheduling problems across the country, with dozens of flights cancelled or delayed. He declared that the threats "were not bad jokes but crimes," and a file was being opened by the police for each threat.

In Paris, the Louvre Museum shut its doors on two separate days, and the Palace of Versailles outside the French capital ushered visitors out — after threats were sent to the famous tourist sites. No incendiary devices were found, but authorities say they are taking all threats seriously.

In Cannes, on the Riviera, a man was arrested Wednesday after he threatened a car dealership manager with a knife. 

France raised its terror alert to the highest level after a teacher was killed in a stabbing at a school on Oct. 13. Investigators said there was no apparent link to the Israel-Gaza conflict, but they were described by the authorities as Islamist terror attacks.