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Editor’s Note: Frida Ghitis, a former CNN producer and correspondent, is a world affairs columnist. She is a frequent opinion contributor to CNN, a contributing columnist to the Washington Post and a columnist for World Politics Review. Follow her on Twitter @fridaghitis. The opinions expressed in this commentary are those of the author. Read more opinion on CNN.

(CNN) —  

On Saturday night, the seventh night of Hannukah, a man entered the home of a rabbi in Monsey, New York, pulled out a machete, and started stabbing worshippers celebrating the Jewish festival of lights. It was at least the ninth attack against Jews in just over a week in the New York area. He was later arrested back in New York City, reportedly covered in blood.

Frida Ghitis
Frida Ghitis

If you think this is a New York problem, or a Jewish problem – or perhaps a far-right, or a far-left, or a black or white problem – you should think again.

History has engraved a lesson about anti-Semitism for all humanity. Anti-Semitism is a symptom of a larger societal problem. Sure, when Jews are unsafe, it is they who are most at risk, but Jews are the canary in the coalmine, an early warning sign of a community or a nation losing its moorings.

The coalmine is filling with toxic fumes.

Soon we will learn more about the alleged perpetrator, who has pleaded not guilty to five counts of attempted murder and one count of burglary. Federal prosecutors have charged him with hate crimes; in the filing of those charges, authorities report finding journals with references to Hitler and a drawing of a swastika and Star of David, as well as a phone used recently to search terms like “German Jewish temples near me” and “Zionist Temples in Elizabeth NJ.” His family says he has a history of mental illness and “was raised in a home which embraced and respected all religions and races.” Whatever his motivation, the rampage focused so brutally on Jews, making it part of a swelling tide of anti-Jewish violence rising across the world. In the US alone, according to the Anti-Defamation League, anti-Semitic attacks doubled last year.

Many of the worst anti-Semitic attacks in recent months and years have been perpetrated by white supremacists, others by Islamist extremists, and several of the recent ones in the New York area by African Americans (including one that expressed interest in the Black Hebrew Israelite movement). Some attackers don’t fit any clear category, other than wanting to massacre Jews. The supposed explanations for these heinous actions often fall into pre-existing slots: white nationalism, refugee and migrant flows, radical Islam, even socio-economic conditions. Across the world, anti-Semitic incidents are sometimes explained or even try to be justified as a reaction to the plight of Palestinians, to racism, or the result of migration from Muslim countries.

But whatever the individual explanation, these attacks are not isolated incidents. They are part of a pattern, a trend. The common denominator is their target: Jews – even if non-Jews often become victims.

Just about every day last week, Jews in New York were punched in the face, slapped, hit, insulted, threatened, goaded, and worse. This is in the United States, a haven for Jews, in New York, where Jews have felt safer than just about anywhere.

The shift is most striking in the US, because from the days of George Washington the country has embraced Jews, making respect and equal citizenship one of the aspirational goals that made America special. Anti-Semitic incidents have occurred throughout America’s history, but something new is happening. Consider recent events.

Last year, the US suffered the deadliest anti-Semitic attack in its history, when a man shouting “All Jews must die,” killed 11 people in Pittsburgh’s Tree of Life synagogue. Last April, someone claiming inspiration from that massacre attacked a synagogue in Poway, California. Just this month, attackers shot at a kosher market in Jersey City, killing three. The city’s mayor said their target might have been 50 children in a Jewish school a few feet away.

Elsewhere, the picture is no less disturbing. As the victims from Friday night remained hospitalized, police in London were investigating more anti-Jewish vandalism, where “911” and Stars of David were painted on Jewish storefronts. (The 911 alludes to another vile theory blaming the September 11 terrorist attack on Jews.) In France, authorities dropped murder charges against a man who tortured and murdered Sarah Halimi, a Jewish kindergarten teacher – calling her a “dirty Jew” and shouting “Allahu Akbar” as he threw her out the window – they claimed he had smoked marijuana and was suffering a psychotic episode as a result.

Anti-Semitism is rising around the world, according to study after study. The increase is most notable in Western democracies, according to a Tel Aviv University report, which noted that the phenomenon is “no longer an issue confined to the activity of the far left, far right and radical Islamists.” Instead, “it has mainstreamed and become an integral part of life.”

That’s why in so many countries, particularly in Europe, Jews have started to “go underground,” hiding traditional skullcaps under baseball caps, surrounding synagogues with armed guards and hiding information about services.

Why is this rise happening now? We are living in a time of conspiracy theories; a time of lies. Politicians and activists are deliberately inflaming differences in society, branding others as not only wrong but dangerous, a threat; sparking fear of “the other.” The ties that used to unite diverse societies, the beliefs and ideals that held communities together are being broken, replaced by ropes to separate, to keep groups apart, making us vulnerable to false stories and frightening theories. Today’s winds whisper that the other is treasonous, menacing.

This is an environment that traditionally leads to problems for Jews, first. If allowed to fester, it can spell much worse for the rest of society.

That’s because Jews have long been favorite subjects of conspiracy theorists. In guarding against such toxic fearmongering, we should learn common conspiratorial tropes so that we can identify them early on, because what might start as jokes, can turn into rumors, and ultimately morph to massacres.

Conspiracy theorists’ tales paint Jews as a sinister force, with great and mysterious hidden powers.

On the left and the right, anti-Semites tend to believe Jews control the world’s finances (That’s how the Jewish billionaire George Soros has become an anti-Semitic dog whistle) . Anti-Semites on the right accuse Jews of running the engine of socialism and migration. Leftist anti-Semites see them as “white,” exploiters of the poor and foes of social justice – that’s a favorite on university campuses. Rightist anti-Semites see them as non-white, not Christian, an enemy within.

On both sides, anti-Semites and those who should know better often claim Jews exaggerate their problems. But history says society benefits from countering the rise in anti-Semitism early on.

Hate crimes against any group cannot be tolerated. But the dramatic increase in anti-Jewish assaults amounts to a flashing light, warning society of its potential to come apart and turn against itself.

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Minimizing, discounting and excusing anti-Semitic attacks is a dangerous path to follow. The US should take the lead in addressing this crisis forcefully, defending, investigating, prosecuting and educating. History has shown that anything else would be much too dangerous, and not just for the Jews.