Last week's attack by a white supremacist on the North Valley Jewish Community Center in Granada Hills has raised concern among American Jews about security at synagogues and other Jewish institutions in the United States.
In many places in Europe and the rest of the world, however, such security considerations have been well-entrenched elements of Jewish institutional infrastructure for decades.
"How could Americans not think of such things?" asked Annie Sacerdoti, editor of Il Bollettino, the magazine of the Jewish community of Milan.
Terrorist attacks by right-wing groups and individuals as well as by Arab and far-left factions dating back to the 1970s have forced many European Jewish communities to take expensive and sometimes elaborate security measures, which by now are routine.
Communities frequently install in-house measures and hire private security companies to supplement protection by local police.
In Rome and Milan, for example, cars are not allowed to park outside synagogues. Police mount an extra guard on the High Holidays and sometimes block off the street. Worshipers have their bags searched, and private security guards stand by with walkie-talkies. Jewish communal institutions feature double security doors and, sometimes, bulletproof glass.
"I have to say that I feel uneasy sometimes at synagogues in the United States," said an American Jew in Rome. "No one checks who enters, and cars are allowed to park on the street right outside."
Rome's main synagogue was the object of a Palestinian terrorist attack in October 1982 that left a toddler dead and many injured.
That attack, which followed the Israeli invasion of Lebanon in June 1982, was part of major waves of anti-Jewish terrorism in Europe in the 1970s and early 1980s.
Most attacks were carried out by Arab or pro-Arab terrorists targeting Jewish institutions as proxies for Israel, but right-wing extremists were responsible for some of the attacks.
In France, synagogues, schools, businesses, memorials and restaurants were hit by bombs in 1976. A bomb in a Paris synagogue on Simchas Torah in 1980 killed four people. Likewise, a bomb in a Jewish-owned restaurant in Berlin in 1980 killed a young child and injured 24.
In 1981, a grenade and machine-gun attack on the main synagogue in Vienna and a car-bomb attack on a synagogue in Antwerp left five dead and more than 100 injured.
In August 1982, a machine-gun attack on a popular Jewish restaurant in Paris killed six people, and a Palestinian attack on the main synagogue in Istanbul in 1986 killed 24 worshipers.
Attacks on Jewish sites and institutions around the world have continued through the 1990s, and the perpetrators frequently have remained anonymous.
Two attacks in Buenos Aires earlier this decade left more than a hundred dead and hundreds others wounded.
The synagogue in Warsaw was firebombed last year, although no one was hurt. Earlier this year, a number of Jews were killed in the bombing of a synagogue in Iraq.
This summer, a bomb was defused before it went off in a Moscow synagogue. The Jewish community there has called on the Russian government to provide greater security for Jewish institutions.