New York Mayor Bill de Blasio on Monday decried a "crisis" of anti-Semitism in the United States after .
"We consider this a crisis," Mr de Blasio said in an interview with NPR radio.
"There is a growing anti-Semitism problem in this whole country.
"It has taken a more and more violent form."
Police work at the home of a rabbi in Monsey, New York after a man entered the house and stabbed multiple people who were there for a Hanukkah gathering. Source: The Journal News
The New York mayor said an "atmosphere of hate" has developed and that the "forces of hate have been unleashed".
"Some of that has to do with the reality of Washington," he said. "Some of it has to do with social media."
Mr De Blasio announced a series of measures to tackle the problem, including an intensified police presence in Jewish communities of New York, additional security cameras and multi-ethnic community safety patrols.
"We have made it a habit when the Jewish community is attacked anywhere in the world to reinforce key Jewish community locations in New York City," he said. "But we're doing it now on a much bigger scale, particularly in Brooklyn, where the most important vulnerabilities are."
A suspect appeared in a New York court on Sunday charged with five counts of attempted murder after the stabbing spree at the suburban house in Monsey, Rockland County, of Rabbi Chaim Rottenberg.
Rockland has the largest Jewish population per capita of any US county, with 31.4 per cent, or 90,000 Jewish residents.
Grafton Thomas, 37, allegedly entered the rabbi's home during celebrations on Saturday evening for Hanukkah, stabbing several people with a machete before fleeing.
Police officers escort suspect Grafton Thomas. Source: FR171675 AP
Still covered in blood, Mr Thomas was reportedly arrested in his car about 50km away, two hours after the attack.
The New York Times quoted Taleea Collins, a friend of the suspect, and his pastor Wendy Paige, as saying Mr Thomas struggles with mental illness.
Last year, - the deadliest attack against the Jewish community in the United States.
Earlier this month, in Jersey City, New Jersey, which authorities said was fueled in part by anti-Semitism.
A report in April from the Anti-Defamation League stated that the number of anti-Semitic attacks in 2018 was close to the record of 2017, with 1879 incidents.
President Donald Trump tweeted that Americans "must all come together to fight, confront, and eradicate the evil scourge of anti-Semitism."
