Anti-Israel extremists painted a symbol used in Hamas propaganda videos to mark Israeli targets on the home of a Jewish museum director in New York.
Anne Pasternak, who runs the Brooklyn Museum, was labelled a "white supremacist Zionist" by activists following weeks of protests against the institution.
Last month, demonstrators from groups including the pro-Palestinian organisation Within Our Lifetime (WOL) hung a banner over the Brooklyn Museum's main entrance calling for it to "divest from genocide".
Thirty four people were detained over ensuing scuffles between the police and protestors, but no charges were filed.
"There was damage to existing and newly installed artwork on our plaza,” a museum spokesperson said .
“Protesters entered the building, and our public safety staff were physically and verbally harassed.”
Earlier this week, anti-Israel activsts in a New York subway carriage were filmed chanting, “raise your hand if you’re a Zionist”.
The footage shows the man leading the call then saying, “this is your chance to get out,” before adding: “Okay, no Zionists, we’re good.”
The chant took place during a “day of rage for Gaza” organised by WOL.
On Wednesday, the Brooklyn Museum protest was extended to Pasternak’s home, which was vandalised with a red triangle painted on its front door.
The symbol has been used by Palestinian militants to indicate Israeli targets in videos shot during the fighting in Gaza.
No group has claimed responsibility for the vandalism.
A series of American politicians condemned the vandalism and vowed to bring those responsible to justice.
NYC Comptroller Brad Lander said: "The cowards who did this are way over the line into antisemitism, harming the cause they claim to care about, and making everyone less safe.”
Mayor Eric Adams said on X/Twitter: “This is not peaceful protest or free speech. This is a crime, and it's overt, unacceptable antisemitism. These actions will never be tolerated in New York City for any reason.
“I'm sorry to Anne Pasternak and members of @brooklynmuseum's board who woke up to hatred like this. I spoke to Anne this morning and committed that this hate will not stand in our city.
“The NYPD is investigating and will bring the criminals responsible here to justice.”
New York governor Kathy Hochul said: “This is an abhorrent act of antisemitism and it has no place in New York or anywhere else.
“We stand with the Jewish community in the face of hate and will continue to fight antisemitism wherever it rears its ugly head."
Speaking to news outlet Democracy Now, however, WOL member Abdullah Akl said the group would continue their campaign.
“[We will] continue to occupy institutions just like this one and call out individuals like the board of the Brooklyn Museum to make clear that their money and our money is being used for this genocide,” he declared.
The Brooklyn Museum said it was, “deeply troubled by these horrible acts.”
In a statement, it added: “For two centuries, the Brooklyn Museum has worked to foster mutual understanding through art and culture, and we have always supported peaceful protest and open, respectful dialogue.
"Violence, vandalism, and intimidation have no place in that discourse.”