12/18/2012 09:20 am ET Updated Feb 17, 2013

Where Neighbors Once Saved Them From the Nazis, Jews Are Now Cautioned to Hide Their Identity

In 1943, at the height of World War II and the Holocaust, the Danish people--under the yoke of German occupation--heroically spirited their Jewish neighbors from the genocidal clutches of the Nazis-- smuggling all 7,500 to safety in neutral Sweden.

Today, a different threatening scenario is unfolding. The streets of Denmark's capital are apparently no longer safe for Jews. It may be too dangerous to openly display your Jewishness in Copenhagen. There is fear of intimidation and violent attack. Israel's ambassador has advised visiting Israelis not to wear yarmulkas, jewelery with Jewish symbols, or even speak Hebrew in public. His is not the only warning. The head teacher at a local private Jewish school, Jan Hansen, reports the Jyllands-Posten, had this advice for students:

"It's not something we advise officially, but we talk about it in informal settings. We advise people to consider the risk before passing through certain neighborhoods in Copenhagen with a skullcap or Star of David."

Police Commissioner Lars-Christian Borg said that Jews, like other "risk groups," for example, homosexuals who want to hold hands, must take precautions:

"If there are areas where you know that there is a conflict and risk of harassment, you have to stay away. It is a shame to say it, but it's some of the advice we give."

The immediate trigger for this crisis may have been a violent demonstration against the Israeli embassy during the latest Hamas-Israel face-off. Spray-painted on its outer wall: "Børne dræbere" ("Child Killers").

Copenhagen is not the only place where European Jews are deeply worried.

In 2010, the Simon Wiesenthal Center slapped a travel advisory on Sweden's third largest city. We reluctantly did so after meeting with its mayor and police chief, who had failed to respond to serial threats and intimidating attacks against the local Rabbi and his young family. Unfortunately, even after the personal intervention of Hannah Rosenthal, the then U.S. State Department Special Envoy on Anti-Semitism, very little has changed. Our travel advisory remains in place and the tiny Jewish community's sense of isolation continues.

In nearby Norway, anti-Semitic attitudes are so deeply entrenched, that authorities admit they are at a loss, and teachers clueless as to how to stop the bullying of Jewish kids in the country's public schools.

Nowhere in Europe is the crisis more acute than in France, home to the continent's largest Jewish Community. The 700,000 Jews are deeply worried about their future, with parents still reeling from the murders of a young rabbi and three children on the schoolyard of a Jewish school in Toulouse and the continuous slurs and attacks on trains, outside of schools and other Jewish institutions. Even with the welcomed beefed-up security measures ordered by France's new Hollande Administration, many parents remain deeply concerned about basic issues like the safety of their kids going to and from school.

We will add Copenhagen to our Travel Advisory list, but the ugliness and dangers of resurgent anti-Semitism in Europe demand much more comprehensive measures.

It is time for the European Union and the European Parliament to forthrightly tackle the growing menace of anti-Jewish hate, intimidation and violence within its borders. Those who promote Jew-hatred in Europe with impunity, whether Islamist radicals, young neo-Nazis, online bigots, or football stadium racists, must know they will be held legally accountable.

Beyond the impact of hate speech, lie real threats of violence and terrorism. While previous spikes in anti-Semitic hate were linked to specific crises in the Middle East, today, the 24/7 online drumbeat of hate demonizes not only the Jewish state, but also Jews and Judaism.

In his often chilling exchange with French police before dying in a hail of bullets, the French Algerian terrorist, Mohammed Merah, wanted it known that he had specifically targeted the kids at a Jewish school because he viewed them as combatants in the war he was fighting.

It is impossible to know how many more"soldiers" like Merah are out there, but this much is clear: For Europeans to allow the conflicts in the volatile Middle East to spill over into their urban centers would wreak chaos and disaster, far beyond the Jewish community.

The late Holocaust survivor and Nazi Hunter Simon Wiesenthal had this warning for society. It was forged from his own tragic personal experiences:

"Beware my friends; the Jews are often the first victims in history, never the last".

As they welcome in 2013, will Europeans heed Mr. Wiesenthal's words?