What is striking about the scandal over the endemic anti-Semitism in the UK Labour Party, which has led to the suspension of 50 party members, is as much the shocking extent of bigotry as the curious timeline of the scandal.

While yet another Labour Party member was suspended just days ago for claiming that “Jews control Britain and are committing genocide on us,” the anti-Semitic comments by elected Labour officials that prompted the current outrage are not new. They were made months and even years ago on social media. Some offenders posted to Facebook about destroying the State of Israel. Another that “Zionist Jews are a disgrace to humanity.” But at the time they were made, no one raised any objections.

Why is that? Because on the far left it has become an acceptable position to oppose the very existence of Israel. In the political echo chambers that social media often create, “relocating” all Israel’s Jews to America seems a justifiable position, even if an implausible one. Comparing Israel to the Nazi perpetrators of the Final Solution is a patently obvious parallel, and accusing Israel of creating or supporting ISIS is reasonable conjecture. It was only when these vile views were exposed to the wider political community that they were they called out – correctly – as anti-Semitic.

But let us not think that this scandal unearths what is a uniquely British problem; it’s a far-left problem, too. And we see similar dynamics at play in other countries across Europe and even here in the U.S.

On the far-right, the anti-Semitism of those who oppose a Jewish state is clear. Neo-Nazi groups, for instance describe Israel as the evil embodiment of all Jews, and accuse it of destroying the United States.

On the far-left advocating the destruction of Israel is often portrayed in terms of ‘justice’ for the Palestinians, masked in a politics of solidarity. Equating Israel with the Nazis serves to underscore Palestinian suffering; and conspiracy theories accusing Israel of backing ISIS makes clear which side of the Israeli-Palestinian conflict deserves the support of well-intentioned people.

Let’s be clear: Israeli policies are fair game for criticism. No state is immune from criticism or its policies beyond reproach. However, there is something profoundly wrong when it has become a legitimate opinion on the far left to question the validity of Israel’s existence, but the attack on Israel’s fundamental legitimacy — the assault on the notion of Israel’s very being and the obsessive demonization and calls for its destruction—have shown themselves to be no less anti-Semitic than the bigotry of the far-right.

Former mayor of London Ken Livingstone, who is now suspended from Labour for absurdly asserting that Hitler supported Zionism, got it exactly wrong when he said, “A real anti-Semite doesn’t just hate the Jews in Israel.” Hating even ‘just’ the Jews in Israel is quite sufficient to qualify you as a ‘real’ anti-Semite.

Contrast his remarks with the actions of London’s first Muslim mayor, Sadiq Kahn, who since his swearing in has attended a Holocaust Remembrance Day ceremony and announced plans to lead a trade delegation to Israel. He’s also criticized Labour for not doing enough to confront anti-Semitism among its members, and spoken of his belief in the importance of strengthening Muslim-Jewish relations in London.

These are admirable gestures that serve as a model for others in positions of political power to emulate.

In addition, the apology of member of parliament Naz Shah, whose 2014 Facebook post about relocating Israel to America launched the current scandal, is instructive. After being elected to Parliament in 2015, she began to meet with her Jewish constituents and moderated her views on Israel. In her well-articulated and moving apology to the Jewish community, she said, “For someone who knows the scourge of oppression and racism all too well, it is important that I make an unequivocal apology for statements and ideas that I have foolishly endorsed in the past… Hindsight is a wonderful thing and I’m shocked myself at the language I used.” Getting out of the echo chamber educates.

UK Labour leader Jeremy Corbyn has declared himself and the party opposed to anti-Semitism, despite his prior embrace of extremist groups like Hamas and Hezbollah whose ideologies invoke tired anti-Semitic stereotypes. Perhaps Mr. Corbyn will clarify how he countenances the hateful rhetoric and violent terrorism of these groups.

Still, Corbyn has ordered an inquiry into anti-Semitism within his party. If the result is an official party report which makes clear that demonization of Israel constitutes anti-Semitism and the assault on its fundamental legitimacy is itself illegitimate, then it will have been a productive exercise. It will have laid down a marker for what is unacceptable for a major political party in a liberal democracy. However, presenting a rote condemnation of anti-Semitism and avoiding the relationship between the anti-Semitic antecedents of left-wing anti-Zionism will be a failure.

Ending anti-Semitism in all its forms, including the demonization of Israel, remains the ultimate goal. But today’s task is to stop the encroaching of anti-Zionism toward a legitimate mainstream position in the global left. Naz Shah may have sparked the controversy, but she also showed the way forward for Labour. Let’s hope her party’s leadership follows her lead.

Jonathan Greenblatt is CEO and National Director of the Anti-Defamation League