Police chiefs in New York this week ordered all personnel to report for duty in uniform on Friday.
It came amid fears of potential attacks on Jewish communities or religious centres in the wake of the horrific events in Israel last weekend and the subsequent Israeli strikes on Gaza.
At the highest levels in the United States there were concerns that Jews could become targets for attack or that tensions between those advocating for Palestinian rights and those defending Israel could spill over into violence.
Last Tuesday US president Joe Biden said that in cities across the US “police departments have stepped up security around centres of Jewish life”.
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“And the department of homeland security and the Federal Bureau of Investigation (FBI) are working closely with state and local law enforcement and Jewish community partners to identify and disrupt any domestic threat that could emerge in connection with these horrific attacks,” he said.
In the aftermath of what an obviously angry and upset Biden described as “pure, unadulterated evil” carried out by Hamas last Saturday, the White House has made it absolutely clear that it fully backs Israel.
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There were no calls for restraint or ceasefires, or attempts to give both sides of the argument.
“Israel has the right to respond – indeed has a duty to respond – to these vicious attacks”, Biden said, although he did urge Israel to respect “the rules of war”.
He said he told Israeli prime minister Binyamin Netanyahu: “If the United States experienced what Israel is experiencing, our response would be swift, decisive and overwhelming.”
More than 20 Americans were killed and others taken prisoner in the attacks last weekend.
There have been a number of pro-Palestinian rallies in some US cities and calls for the historical context of the conflict to be taken into account.
But in the main, politically, there has been across-the-board revulsion at the attacks by Hamas. Stories and images of murdered babies received extensive coverage.
Former president Donald Trump adopted a different tone – criticising Netanyahu (attributed by some media to an ongoing grievance over the Israeli prime minister congratulating Biden on winning the 2020 election) and describing the Lebanese militant group Hizbullah as “very smart”.
However, it is on some US college campuses – where student groups had a history of backing rights for Palestine – that a different perspective has been seen.
At the prestigious Harvard University, a group of about 30 student organisations said “they hold the Israeli regime entirely responsible for all unfolding violence”.
A student group at the University of Virginia maintained that the Hamas attack represented “a step towards a free Palestine”.
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The students’ comments provoked outrage in some quarters, with suggestions that those who signed the statements should essentially face an employment blacklist, while there were also warnings that it could lead to alumni keeping their chequebooks closed in future – and denying the universities concerned a lucrative source of funding.
The potential for events in Israel and Gaza leading to a violent backlash against Jews in the United States seems to be worrying authorities in Washington.
At an event with Jewish community leaders attended by the president on Wednesday, US second gentleman Doug Emhoff – husband of vice-president Kamala Harris – said “many of us feel a deep fear that these attacks will unfortunately, and already have, led to a rise in hate and anti-Semitism.
“We’re already seeing it.”
There have been a number of serious attacks on Jews, and other anti-Jewish incidents, in the US in recent years – the mostly deadly being the massacre at the Tree of Life synagogue in Pittsburgh in 2018.
In August, a man convicted of killing 11 people in the gun attack on the synagogue was sentenced to death.
In 2017, the sight of neo-Nazis marching through Charlottesville in Virginia chanting “Jews will not replace us” caused consternation.
A US government report published in May cited comments last year by the head of the FBI that while American Jews accounted for 2.4 per cent of the population, anti-Semitism drove 63 per cent of reported religiously-motivated hate crimes.
Biden said he had asked his homeland security secretary and his attorney general “to set up security around Jewish life in United States – identify, prevent, and disrupt emerging threats that occur”.
He said his administration would continue to condemn and combat anti-Semitism at every single turn.
“I used to think you could defeat hate, that you could make it [go away]. All it does is go underground. It just goes underground. It doesn’t go away. It only hides until it’s given a little oxygen – a little bit of oxygen.”