London’s mayor has crossed a far more dangerous line than Mamdani

New York City Mayor Zohran Mamdani dominated headlines this past week after pledging to arrest Israeli Prime Minister Benjamin Netanyahu should he visit New York for the United Nations General Assembly in September.

The comments were inflammatory and dangerous. But they were also legally meaningless.

The far more serious warning came across the Atlantic.

London Mayor Sadiq Khan has now labeled Netanyahu “a perpetrator of genocide” and said he would urge the British government to arrest the Israeli prime minister should he visit the United Kingdom. Unlike the United States, the UK is a founding member of the International Criminal Court and a State Party to the Rome Statute. That makes Khan’s comments far more consequential than Mamdani’s political theatre.

Mamdani and his team have mastered the art of commanding headlines. Every statement, social media video, and campaign pledge seems carefully calibrated to dominate the news cycle.

His latest proposal, however, unraveled almost immediately. A mayor whose responsibilities centre on municipal services and public safety cannot arrest a democratically elected foreign head of government enjoying diplomatic protections while attending an international gathering of 193 world leaders, including dozens of dictators and authoritarians who somehow escaped Mamdani’s selective moral scrutiny.

That does not mean his rhetoric is harmless.

Words from the leader of one of the world’s greatest cities carry enormous weight. In today’s digital age, political statements ricochet across social media within seconds, often inflaming passions long before facts catch up.

Only days after Mamdani’s callous remarks, an observant Jew and an Asian man were stabbed in Manhattan’s Upper West Side by a crazed assailant who allegedly shouted “Allahu Akbar.” The NYPD classified the attack on the Jewish victim as a hate crime.

Legally, however, Mamdani’s pledge was always empty. The United States has never ratified the Rome Statute and does not recognise the jurisdiction of the ICC. As the U.S. Department of Justice has long maintained, “a treaty cannot bind a non-consenting country.” Accordingly, the ICC has no jurisdiction over Americans—or Israelis—and any attempt to exercise such authority is unlawful and an affront to American sovereignty.

The ICC warrant itself also rests on increasingly shaky foundations. It was issued by former chief prosecutor Karim Khan just days before allegations of sexual misconduct against him became public. Earlier this week, ICC member states voted overwhelmingly to remove Khan from office following his suspension.

One might have expected the backlash to Mamdani’s remarks to discourage other political leaders from embracing similar rhetoric.

Instead, London Mayor Sadiq Khan has chosen to follow the same script.

Words from the leader of one of the world’s greatest cities carry enormous weight. In today’s digital age, political statements ricochet across social media within seconds

The timing makes his comments all the more disturbing. Only days earlier, Khan visited London’s Nova Music Festival exhibition and urged visitors to remember “the horrors of that awful day” on October 7. Yet within a week he publicly declared Netanyahu “a perpetrator of genocide” and insisted he should be arrested if he visits Britain.

“As a perpetrator of genocide,” Khan said, “I think he’s broken the law. And I think justice needs to happen, and that means him being brought to book.”

Unlike Mamdani’s remarks, these comments carry genuine diplomatic significance. Britain is legally bound by the Rome Statute and has long presented itself as a champion of the international legal order. When the mayor of one of the world’s leading capitals publicly calls for the arrest of the democratically elected leader of a close ally, it lends credibility to an ICC process that many legal experts and democratic governments have questioned.

It also comes at a moment when antisemitism has become disturbingly commonplace across Britain. In the past year alone, Jews have endured stabbings in Golders Green, attempted arson attacks on synagogues, the destruction of Hatzolah ambulances, and the killing of two Jewish men in Manchester during Yom Kippur. Against that backdrop, rhetoric that singles out the Jewish state’s leader while ignoring the world’s countless genuine war criminals risks reinforcing an already dangerous climate.

Demonising Israel has become an easy route to headlines and political applause. Mamdani turned it into political theatre in New York. Sadiq Khan has now elevated it into something with potentially serious diplomatic consequences.

When elected leaders compete to lambast Israel, they do more than dominate the news cycle. They help normalise the hostility that Jews increasingly confront on the streets of New York, London, Sydney, Vancouver and beyond.

Mamdani’s comments generated headlines. Sadiq Khan’s could shape policy. That is why London, not just New York, should be where the real alarm bells are ringing.

• Jonathan Harounoff is a British journalist covering the Middle East, who has been serving as Israel’s International Spokesperson to the UN since September 2024