American Jews have been rocked in recent weeks by a wave of anti-Semitic incidents, including bomb threats and cemetery desecrations.
These kinds of attacks are not supposed to happen in the Jewish utopia of the United States, and suddenly the sense of insecurity felt by European Jewish communities in recent years seems to be making its way across the Atlantic.
This isn’t helped by the fact that President Trump was initially slow to condemn the attacks, and then, bizarrely, appeared to blame Jews, Democrats or anyone other than anti-Semites for carrying them out in order to damage him and his supporters.
“Someone’s doing it to make others look bad,” Trump was reported as saying on a conference call with state attorneys general from across America.
It might be anti-Semites perpetrating these incidents, or “the reverse can be true,” he said.
It’s typical of Trump to make everything – even the desecration of Jewish cemeteries – about himself, but the allegation that Jews or others carry out ‘false flag’ anti-Semitic attacks for political benefit is a conspiracy theory that is very common on the far right.
Coincidentally, or perhaps not, a lot of the anti-Semites on the American far right are currently delighted with Trump’s presidency.
It shouldn’t be a surprise that Trump, who regularly echoes conspiracy theories and appears contemptuous of the very idea there is such a thing as ‘fact’, could come out with such a strange suggestion; but it is certainly alarming.
It is a common mistake to view conspiracy theorists as wacky, or stupid, but usually harmless.
Conspiracy theories are an essential component of fanaticism, and when fanatics get power their capacity for harm is limitless.
Trump’s attempt to deflect the question of anti-Semitism is not a problem confined to the far right.
On the left, too, people will make any excuse for anti-Semitism if it suits their political interests to do so.
Here in Britain, some supporters of Jeremy Corbyn doggedly insist that accusations of anti-Semitism in the Labour Party have been invented by Corbyn’s opponents to make trouble for him.
“How the Israel lobby fakes anti-Semitism”, screams a headline on the Electronic Intifada website.
One of its writers, Asa Winstanley, alleges that claims of anti-Semitism in the Labour Party are “false”, “exaggerated” and “wholly fabricated”.
Jonathan Rosenhead, from the anti-Zionist ‘Free Speech On Israel’ blog, says that evidence for anti-Semitism in Labour is absent, but “one solution if you want a crisis and lack enough evidence is to invent some.”
I don’t know whether Winstanley and Rosenhead really think that supporters of Israel are ‘fabricating’ evidence of anti-Semitism, perhaps by going onto social media, pretending to be Corbynites, and making up anti-Semitic posts.
Nor do I know whether Trump really believes that American Jews, or Democrats, or some other group who dislikes him, are behind the hundreds of anti-Semitic incidents recorded in America since his election.
What is apparent, though, is that all three seem to be more interested in protecting their own political interests than in genuinely addressing the problem of anti-Semitism.
In this time of political polarisation, I’m sure that Jeremy Corbyn, Donald Trump, and their various supporters, would shudder at the idea they have anything in common.
In many ways, they couldn’t be more distinct.
But one thing unites them: while both left and right are quick to point out anti-Semitism in each other’s movements, they stubbornly refuse to see it in their own if it is politically inconvenient to do so.
The feeling of bewilderment and betrayal felt by many Labour-supporting Jews over the past two years is now finding its echo amongst American Jews.
Jonathan Greenblatt, head of the Anti-Defamation League, said he was “astonished” at Trump’s comments apparently directing blame away from anti-Semites for the wave of anti-Semitic incidents, and called for urgent clarification.
Sadly there is nothing in Trump’s record to suggest he will stop making such destabilising statements.
His Chief Strategist, Steve Bannon, appears to view history as one in which periodic conflicts destroy the old order and give birth to the new: and he thinks the time is ripe for the next turn of the wheel.
Meanwhile the social media accounts and blogs of the Corbynite Left fill up with conspiracy theories about Rothschild bankers and Zionist manipulators.
In such times, the notion that Jews desecrate their own cemeteries and send bomb threats to their own schools, or that they invent anti-Semitic incidents in the Labour Party, is likely to be believed by more people than we might imagine.