Since the outbreak of fighting between Israel and Hamas in Gaza, there's been a wave of street-level demonstrations rallying against the war. These protestors are generally highly critical of Israel and blame it for the current round of violence, but the vast majority want an end to the violence and are demanding it peacefully.

But the peaceful demonstrators are not alone in turning out to the streets over the Israel-Gaza conflict. A small-but-disturbing fraction of the international anger over the war has escalated into outright anti-Semitism: shouting "gas the Jews!" during protests in Germany, attacking synagogues in France, and beating a rabbi in Morocco. These attacks are not new: they come at time when anti-Semitic incidents around the world are worryingly on the rise.

To give you a sense of what's going on, here are incidents from four different countries of anti-Semitism during the ongoing Israel-Hamas conflict. The worst reported upswing in anti-Semitism has been in Europe, particularly France, and three of the countries we examine are on the continent.

France

France has the third-largest Jewish population in the world, after the United States and Israel. It appears to have seen the worst anti-Semitic violence in recent days.

"Eight synagogues in France have been targeted in the past week," The New York Times reports. Over the July 19-20th weekend, "a radical fringe among pro-Palestinian protesters in the French capital clashed with police, targeting Jewish shops, lighting smoke bombs, and throwing stones and bottles at riot police," the Times reported.

"They are not screaming 'death to the Israelis' on the streets of Paris, " Roger Cuikerman, head of French Jewish political group CRIF, said. "They are screaming ‘death to the Jews.'"

According to The Independent, a peaceful protest in the northern Paris suburb Saracelles "degenerated" into anti-Semitic violence. "Several cars were burned," the Independent reported, and "three shops, including a Kosher grocery, were burned and pillaged. A railway station was severely damaged."

It's gotten so bad that French authorities outright banned protests in certain parts of Paris. Prime Minister Manuel Valls warned of a "new form of anti-Semitism" taking hold in the country.

Germany

According to the Associated Press, anti-Semitic slogans have popped up in protests inside Germany. "Gas the Jews," has been chanted at some protests, according to the Associated Press.

Though Germany hasn't seen French-style mass rioting, the German Jewish community is understandably worried. "Never in our lives did we believe it possible that anti-Semitism of the most primitive kind would be heard on the streets of Germany," Dieter Graumann, president of the Central Council of Jews in Germany, told reporters.

It's worth noting that German anti-Semitism isn't confined to a lunatic fringe. A sophisticated analysis of anti-Semitic hate mail sent to the Central Council from 2002 to 2012, much of which was Israel-related, found that 60 percent of the mail originated with "well-educated Germans, including university professors." Only three percent came from the right-wing fringe.

Morocco

A young man beat up Rabbi Moshe Ohayon in Casablanca, the north African country's most populous city. According to Agence France-Press, the attack was motivated by the ongoing violence in Israel. Three of the rabbi's ribs were broken.

"Are you Jewish?", the assailant allegedly asked. "What's the Tsahal (Israeli army) doing to our brothers?"

The Netherlands

Unidentified assailants attacked the home of Rabbi Binyomin Jacobs, the Dutch Chief Rabbi, twice in one week. The first caused no damage, but in the second, several thrown stones shattered windows.

'We have been warning for a long time about the severe rise of anti-Semitism across Europe'

It's not yet clear why the attacks happened or who the perpetrators were. But the European Jewish community is nonetheless worried that this may be part of a broader pattern.

"We have been warning for a long time about the severe rise of anti-Semitism across Europe," Rabbi Menachem Margolin, Director General of the European Jewish Association, said after the attack on Rabbi Jacobs. And he's not wrong.

Anti-Semitism has been on the rise

The best data on anti-Semitic incidents, from the Kantor Center at Tel Aviv University, suggests there's been a general trend towards more anti-Semitic attacks worldwide over the past 25 years:

About 30 percent of the attacks in 2012, the last year data was recorded, took place in France. Unsurprisingly, places with higher Jewish populations tended to see higher levels of anti-Semitic violence. The United States, luckily, was immune to this trend — there's actually been a decline in anti-Semitic attacks since 1994, according to Anti-Defamation League data.

You'll also notice a huge spike in anti-Semitic incidents in 2009. According to Ohio State sociologist William Brustein, that, too, was related to Israeli-Palestinian violence. Israel invaded Gaza in January 2009, and anger at the war, particularly in Europe, prompted the upswing in violence. On Thursday, Israel launched its first invasion of Gaza since the 2009 conflict.

Luckily, Brustein believes there's not likely to be a sustained trend in anti-Semitic violence. "The underlying roots and motivators [of anti-Semitism] have been eliminated or declined," he said. Mainstream Christian doctrine is no longer anti-Semitic, fewer people believe anti-Semitic conspiracy theories, and Nazi-style racial hatred is no longer in power. It's a welcome reminder amidst troubling news.